[v6,00/14] CSI2RX support on J721E

Hi,

This series adds support for CSI2 capture on J721E. It includes some
fixes to the Cadence CSI2RX driver, re-structures the TI platform
drivers, and finally adds the TI CSI2RX wrapper driver.

This series used to include the DPHY and DMA engine patches as well, but
they have been split off to facilitate easier merging.

Tested on TI's J721E with OV5640 sensor.

The branch with all the patches needed to enable testing (dts nodes,
OV5640 dropped patch, etc.) can be found here at
https://github.com/prati0100/linux-next/ branch "capture".

Changes in v6:
- Move the lock around the dereference for framefmt in
  csi2rx_{get,set}_fmt() instead of when we get the pointer.
- Do not return an error when an unsupported format is set. Instead
  adjust the code to the first format in the list.
- Drop variable bpp and use fmt->bpp directly.
- Drop variable got_pm. Call phy_pm_runtime_put() unconditionally since
  it will just return an error if runtime PM is not enabled.
- Drop transcoding from the commit message.
- Make csi2rx_media_ops const.

Changes in v5:
- Cleanup notifier in csi2rx_parse_dt() after the call to
  v4l2_async_nf_add_fwnode_remote().
- Use YUV 1X16 formats instead of 2X8.
- Only error out when phy_pm_runtime_get_sync() returns a negative
  value. A positive value can be returned if the phy was already
  resumed.
- Do not query the source subdev for format. Use the newly added
  internal format instead.
- Make i unsigned.
- Change %d to %u
- Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
  since the Rx mode DPHY now has a separate driver.
- Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be done
  at media_pipeline_start().
- Do not assign flags.
- Fix error handling in ti_csi2rx_start_streaming(). Free up vb2 buffers
  when media_pipeline_start() fails.
- Move clock description in comments under the clocks property.
- Make ports required.
- Add link validation to cdns-csi2rx driver.

Changes in v4:
- Drop the call to set PHY submode. It is now being done via compatible
  on the DPHY side.
- Acquire the media device's graph_mutex before starting the graph walk.
- Call media_graph_walk_init() and media_graph_walk_cleanup() when
  starting and ending the graph walk respectively.
- Reduce max frame height and width in enum_framesizes. Currently they
  are set to UINT_MAX but they must be a multiple of step_width, so they
  need to be rounded down. Also, these values are absurdly large which
  causes some userspace applications like gstreamer to trip up. While it
  is not generally right to change the kernel for an application bug, it
  is not such a big deal here. This change is replacing one set of
  absurdly large arbitrary values with another set of smaller but still
  absurdly large arbitrary values. Both limits are unlikely to be hit in
  practice.
- Add power-domains property.
- Drop maxItems from clock-names.
- Drop the type for data-lanes.
- Drop uniqueItems from data-lanes. Move it to video-interfaces.yaml
  instead.
- Drop OV5640 runtime pm patch. It seems to be a bit complicated and it
  is not exactly necessary for this series. Any CSI-2 camera will work
  just fine, OV5640 just happens to be the one I tested with. I don't
  want it to block this series. I will submit it as a separate patch
  later.

Changes in v3:
- Use v4l2_get_link_freq() to calculate pixel clock.
- Move DMA related fields in struct ti_csi2rx_dma.
- Protect DMA buffer queue with a spinlock to make sure the queue buffer
  and DMA callback don't race on it.
- Track the current DMA state. It might go idle because of a lack of
  buffers. This state can be used to restart it if needed.
- Do not include the current buffer in the pending queue. It is slightly
  better modelling than leaving it at the head of the pending queue.
- Use the buffer as the callback argument, and add a reference to csi in it.
- If queueing a buffer to DMA fails, the buffer gets leaked and DMA gets
  stalled with. Instead, report the error to vb2 and queue the next
  buffer in the pending queue.
- DMA gets stalled if we run out of buffers since the callback is the
  only one that fires subsequent transfers and it is no longer being
  called. Check for that when queueing buffers and restart DMA if
  needed.
- Do not put of node until we are done using the fwnode.
- Set inital format to UYVY 640x480.
- Add compatible: contains: const: cdns,csi2rx to allow SoC specific
  compatible.
- Add more constraints for data-lanes property.

Changes in v2:
- Use phy_pm_runtime_get_sync() and phy_pm_runtime_put() before making
  calls to set PHY mode, etc. to make sure it is ready.
- Use dmaengine_get_dma_device() instead of directly accessing
  dma->device->dev.
- Do not set dst_addr_width when configuring slave DMA.
- Move to a separate subdir and rename to j721e-csi2rx.c
- Convert compatible to ti,j721e-csi2rx.
- Move to use Media Controller centric APIs.
- Improve cleanup in probe when one of the steps fails.
- Add colorspace to formats database.
- Set hw_revision on media_device.
- Move video device initialization to probe time instead of register time.
- Rename to ti,j721e-csi2rx.yaml
- Add an entry in MAINTAINERS.
- Add a description for the binding.
- Change compatible to ti,j721e-csi2rx to make it SoC specific.
- Remove description from dmas, reg, power-domains.
- Remove a limit of 2 from #address-cells and #size-cells.
- Fix add ^ to csi-bridge subnode regex.
- Make ranges mandatory.
- Add unit address in example.
- Add a reference to cdns,csi2rx in csi-bridge subnode.
- Expand the example to include the csi-bridge subnode as well.
- Re-order subject prefixes.
- Convert OV5640 to use runtime PM and drop Cadence CSI2RX s_power patch.
- Drop subdev call wrappers from cdns-csi2rx.
- Move VPE and CAL to a separate subdir.
- Rename ti-csi2rx.c to j721e-csi2rx.c

Pratyush Yadav (14):
  media: cadence: csi2rx: Unregister v4l2 async notifier
  media: cadence: csi2rx: Cleanup media entity properly
  media: cadence: csi2rx: Add get_fmt and set_fmt pad ops
  media: cadence: csi2rx: Add external DPHY support
  media: cadence: csi2rx: Soft reset the streams before starting capture
  media: cadence: csi2rx: Set the STOP bit when stopping a stream
  media: cadence: csi2rx: Fix stream data configuration
  media: cadence: csi2rx: Populate subdev devnode
  media: cadence: csi2rx: Add link validation
  media: Re-structure TI platform drivers
  media: ti: Add CSI2RX support for J721E
  media: dt-bindings: Make sure items in data-lanes are unique
  media: dt-bindings: Add DT bindings for TI J721E CSI2RX driver
  media: dt-bindings: Convert Cadence CSI2RX binding to YAML

 .../devicetree/bindings/media/cdns,csi2rx.txt | 100 --
 .../bindings/media/cdns,csi2rx.yaml           | 176 ++++
 .../bindings/media/ti,j721e-csi2rx.yaml       | 101 ++
 .../bindings/media/video-interfaces.yaml      |   1 +
 MAINTAINERS                                   |  10 +-
 drivers/media/platform/Kconfig                |  12 +
 drivers/media/platform/Makefile               |   2 +-
 drivers/media/platform/cadence/cdns-csi2rx.c  | 274 +++++-
 drivers/media/platform/ti/Makefile            |   4 +
 drivers/media/platform/ti/cal/Makefile        |   3 +
 .../{ti-vpe => ti/cal}/cal-camerarx.c         |   0
 .../platform/{ti-vpe => ti/cal}/cal-video.c   |   0
 .../media/platform/{ti-vpe => ti/cal}/cal.c   |   0
 .../media/platform/{ti-vpe => ti/cal}/cal.h   |   0
 .../platform/{ti-vpe => ti/cal}/cal_regs.h    |   0
 .../media/platform/ti/j721e-csi2rx/Makefile   |   2 +
 .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 913 ++++++++++++++++++
 .../platform/{ti-vpe => ti/vpe}/Makefile      |   4 -
 .../media/platform/{ti-vpe => ti/vpe}/csc.c   |   0
 .../media/platform/{ti-vpe => ti/vpe}/csc.h   |   0
 .../media/platform/{ti-vpe => ti/vpe}/sc.c    |   0
 .../media/platform/{ti-vpe => ti/vpe}/sc.h    |   0
 .../platform/{ti-vpe => ti/vpe}/sc_coeff.h    |   0
 .../media/platform/{ti-vpe => ti/vpe}/vpdma.c |   0
 .../media/platform/{ti-vpe => ti/vpe}/vpdma.h |   0
 .../platform/{ti-vpe => ti/vpe}/vpdma_priv.h  |   0
 .../media/platform/{ti-vpe => ti/vpe}/vpe.c   |   0
 .../platform/{ti-vpe => ti/vpe}/vpe_regs.h    |   0
 28 files changed, 1481 insertions(+), 121 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/media/cdns,csi2rx.txt
 create mode 100644 Documentation/devicetree/bindings/media/cdns,csi2rx.yaml
 create mode 100644 Documentation/devicetree/bindings/media/ti,j721e-csi2rx.yaml
 create mode 100644 drivers/media/platform/ti/Makefile
 create mode 100644 drivers/media/platform/ti/cal/Makefile
 rename drivers/media/platform/{ti-vpe => ti/cal}/cal-camerarx.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/cal}/cal-video.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/cal}/cal.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/cal}/cal.h (100%)
 rename drivers/media/platform/{ti-vpe => ti/cal}/cal_regs.h (100%)
 create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
 create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
 rename drivers/media/platform/{ti-vpe => ti/vpe}/Makefile (78%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/csc.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/csc.h (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/sc.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/sc.h (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/sc_coeff.h (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma.h (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma_priv.h (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/vpe.c (100%)
 rename drivers/media/platform/{ti-vpe => ti/vpe}/vpe_regs.h (100%)

Hi Pratyush,

Thank you for the patch.

On Fri, Jan 21, 2022 at 07:58:53PM +0530, Pratyush Yadav wrote:
> The format is needed to calculate the link speed for the external DPHY
> configuration. It is not right to query the format from the source
> subdev. Add get_fmt and set_fmt pad operations so that the format can be
> configured and correct bpp be selected.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> 
> Changes in v6:
> - Move the lock around the dereference for framefmt in
>   csi2rx_{get,set}_fmt() instead of when we get the pointer.
> - Do not return an error when an unsupported format is set. Instead
>   adjust the code to the first format in the list.
> - Not adding Laurent's R-by since I am making changes in
>   csi2rx_set_fmt() that he didn't explicitly recommend.
> 
> Changes in v5:
> - Use YUV 1X16 formats instead of 2X8.
> - New in v5.
> 
>  drivers/media/platform/cadence/cdns-csi2rx.c | 131 +++++++++++++++++++
>  1 file changed, 131 insertions(+)
> 
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index 2547903f2e8e..ae3ebdb3890d 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -54,6 +54,11 @@ enum csi2rx_pads {
>  	CSI2RX_PAD_MAX,
>  };
>  
> +struct csi2rx_fmt {
> +	u32				code;
> +	u8				bpp;
> +};
> +
>  struct csi2rx_priv {
>  	struct device			*dev;
>  	unsigned int			count;
> @@ -79,12 +84,43 @@ struct csi2rx_priv {
>  	struct v4l2_subdev		subdev;
>  	struct v4l2_async_notifier	notifier;
>  	struct media_pad		pads[CSI2RX_PAD_MAX];
> +	struct v4l2_mbus_framefmt	fmt;
>  
>  	/* Remote source */
>  	struct v4l2_subdev		*source_subdev;
>  	int				source_pad;
>  };
>  
> +static const struct csi2rx_fmt formats[] = {
> +	{
> +		.code	= MEDIA_BUS_FMT_YUYV8_1X16,
> +		.bpp	= 16,
> +	},
> +	{
> +		.code	= MEDIA_BUS_FMT_UYVY8_1X16,
> +		.bpp	= 16,
> +	},
> +	{
> +		.code	= MEDIA_BUS_FMT_YVYU8_1X16,
> +		.bpp	= 16,
> +	},
> +	{
> +		.code	= MEDIA_BUS_FMT_VYUY8_1X16,
> +		.bpp	= 16,
> +	},
> +};
> +
> +static const struct csi2rx_fmt *csi2rx_get_fmt_by_code(u32 code)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(formats); i++)
> +		if (formats[i].code == code)
> +			return &formats[i];
> +
> +	return NULL;
> +}
> +
>  static inline
>  struct csi2rx_priv *v4l2_subdev_to_csi2rx(struct v4l2_subdev *subdev)
>  {
> @@ -236,12 +272,103 @@ static int csi2rx_s_stream(struct v4l2_subdev *subdev, int enable)
>  	return ret;
>  }
>  
> +static struct v4l2_mbus_framefmt *
> +csi2rx_get_pad_format(struct csi2rx_priv *csi2rx,
> +		      struct v4l2_subdev_state *state,
> +		      unsigned int pad, u32 which)
> +{
> +	switch (which) {
> +	case V4L2_SUBDEV_FORMAT_TRY:
> +		return v4l2_subdev_get_try_format(&csi2rx->subdev, state, pad);
> +	case V4L2_SUBDEV_FORMAT_ACTIVE:
> +		return &csi2rx->fmt;
> +	default:
> +		return NULL;
> +	}
> +}
> +
> +static int csi2rx_get_fmt(struct v4l2_subdev *subdev,
> +			  struct v4l2_subdev_state *state,
> +			  struct v4l2_subdev_format *format)
> +{
> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
> +	struct v4l2_mbus_framefmt *framefmt;
> +
> +	framefmt = csi2rx_get_pad_format(csi2rx, state, format->pad,
> +					 format->which);
> +	if (!framefmt)
> +		return -EINVAL;
> +
> +	mutex_lock(&csi2rx->lock);
> +	format->format = *framefmt;
> +	mutex_unlock(&csi2rx->lock);
> +
> +	return 0;
> +}
> +
> +static int csi2rx_set_fmt(struct v4l2_subdev *subdev,
> +			  struct v4l2_subdev_state *state,
> +			  struct v4l2_subdev_format *format)
> +{
> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
> +	struct v4l2_mbus_framefmt *framefmt;
> +
> +	/* No transcoding, source and sink formats must match. */
> +	if (format->pad != CSI2RX_PAD_SINK)
> +		return csi2rx_get_fmt(subdev, state, format);
> +
> +	if (!csi2rx_get_fmt_by_code(format->format.code))
> +		format->format.code = formats[0].code;
> +
> +	format->format.field = V4L2_FIELD_NONE;
> +
> +	framefmt = csi2rx_get_pad_format(csi2rx, state, format->pad,
> +					 format->which);
> +	if (!framefmt)
> +		return -EINVAL;
> +
> +	mutex_lock(&csi2rx->lock);
> +	*framefmt = format->format;
> +	mutex_unlock(&csi2rx->lock);
> +
> +	return 0;
> +}
> +
> +static int csi2rx_init_cfg(struct v4l2_subdev *subdev,
> +			   struct v4l2_subdev_state *state)
> +{
> +	struct v4l2_subdev_format format = {
> +		.which = state ? V4L2_SUBDEV_FORMAT_TRY
> +			: V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.pad = CSI2RX_PAD_SINK,
> +		.format = {
> +			.width = 640,
> +			.height = 480,
> +			.code = MEDIA_BUS_FMT_UYVY8_1X16,
> +			.field = V4L2_FIELD_NONE,
> +			.colorspace = V4L2_COLORSPACE_SRGB,
> +			.ycbcr_enc = V4L2_YCBCR_ENC_601,
> +			.quantization = V4L2_QUANTIZATION_LIM_RANGE,
> +			.xfer_func = V4L2_XFER_FUNC_SRGB,
> +		},
> +	};
> +
> +	return csi2rx_set_fmt(subdev, state, &format);
> +}
> +
> +static const struct v4l2_subdev_pad_ops csi2rx_pad_ops = {
> +	.get_fmt	= csi2rx_get_fmt,
> +	.set_fmt	= csi2rx_set_fmt,
> +	.init_cfg	= csi2rx_init_cfg,
> +};
> +
>  static const struct v4l2_subdev_video_ops csi2rx_video_ops = {
>  	.s_stream	= csi2rx_s_stream,
>  };
>  
>  static const struct v4l2_subdev_ops csi2rx_subdev_ops = {
>  	.video		= &csi2rx_video_ops,
> +	.pad		= &csi2rx_pad_ops,
>  };
>  
>  static int csi2rx_async_bound(struct v4l2_async_notifier *notifier,
> @@ -457,6 +584,10 @@ static int csi2rx_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err_cleanup;
>  
> +	ret = csi2rx_init_cfg(&csi2rx->subdev, NULL);
> +	if (ret)
> +		goto err_cleanup;
> +
>  	ret = v4l2_async_register_subdev(&csi2rx->subdev);
>  	if (ret < 0)
>  		goto err_cleanup;

Hi Pratyush,

Thank you for the patch.

On Fri, Jan 21, 2022 at 07:59:01PM +0530, Pratyush Yadav wrote:
> TI's J721E uses the Cadence CSI2RX and DPHY peripherals to facilitate
> capture over a CSI-2 bus.
> 
> The Cadence CSI2RX IP acts as a bridge between the TI specific parts and
> the CSI-2 protocol parts. TI then has a wrapper on top of this bridge
> called the SHIM layer. It takes in data from stream 0, repacks it, and
> sends it to memory over PSI-L DMA.
> 
> This driver acts as the "front end" to V4L2 client applications. It
> implements the required ioctls and buffer operations, passes the
> necessary calls on to the bridge, programs the SHIM layer, and performs
> DMA via the dmaengine API to finally return the data to a buffer
> supplied by the application.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> 
> ---
> 
> (no changes since v5)
> 
> Changes in v5:
> - Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
>   since the Rx mode DPHY now has a separate driver.
> - Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be done
>   at media_pipeline_start().
> - Do not assign flags.
> - Fix error handling in ti_csi2rx_start_streaming(). Free up vb2 buffers
>   when media_pipeline_start() fails.
> 
> Changes in v4:
> - Acquire the media device's graph_mutex before starting the graph walk.
> - Call media_graph_walk_init() and media_graph_walk_cleanup() when
>   starting and ending the graph walk respectively.
> - Reduce max frame height and width in enum_framesizes. Currently they
>   are set to UINT_MAX but they must be a multiple of step_width, so they
>   need to be rounded down. Also, these values are absurdly large which
>   causes some userspace applications like gstreamer to trip up. While it
>   is not generally right to change the kernel for an application bug, it
>   is not such a big deal here. This change is replacing one set of
>   absurdly large arbitrary values with another set of smaller but still
>   absurdly large arbitrary values. Both limits are unlikely to be hit in
>   practice.
> 
> Changes in v3:
> - Move DMA related fields in struct ti_csi2rx_dma.
> - Protect DMA buffer queue with a spinlock to make sure the queue buffer
>   and DMA callback don't race on it.
> - Track the current DMA state. It might go idle because of a lack of
>   buffers. This state can be used to restart it if needed.
> - Do not include the current buffer in the pending queue. It is slightly
>   better modelling than leaving it at the head of the pending queue.
> - Use the buffer as the callback argument, and add a reference to csi in it.
> - If queueing a buffer to DMA fails, the buffer gets leaked and DMA gets
>   stalled with. Instead, report the error to vb2 and queue the next
>   buffer in the pending queue.
> - DMA gets stalled if we run out of buffers since the callback is the
>   only one that fires subsequent transfers and it is no longer being
>   called. Check for that when queueing buffers and restart DMA if
>   needed.
> - Do not put of node until we are done using the fwnode.
> - Set inital format to UYVY 640x480.
> 
> Changes in v2:
> - Use dmaengine_get_dma_device() instead of directly accessing
>   dma->device->dev.
> - Do not set dst_addr_width when configuring slave DMA.
> - Move to a separate subdir and rename to j721e-csi2rx.c
> - Convert compatible to ti,j721e-csi2rx.
> - Move to use Media Controller centric APIs.
> - Improve cleanup in probe when one of the steps fails.
> - Add colorspace to formats database.
> - Set hw_revision on media_device.
> - Move video device initialization to probe time instead of register time.
> 
>  MAINTAINERS                                   |   6 +
>  drivers/media/platform/Kconfig                |  12 +
>  drivers/media/platform/ti/Makefile            |   1 +
>  .../media/platform/ti/j721e-csi2rx/Makefile   |   2 +
>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 913 ++++++++++++++++++
>  5 files changed, 934 insertions(+)
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3b8fa4e5047f..2a8ebf17462e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19181,6 +19181,12 @@ S:	Odd Fixes
>  F:	drivers/clk/ti/
>  F:	include/linux/clk/ti.h
>  
> +TI J721E CSI2RX DRIVER
> +M:	Pratyush Yadav <p.yadav@ti.com>
> +L:	linux-media@vger.kernel.org
> +S:	Supported
> +F:	drivers/media/platform/ti/j721e-csi2rx/
> +
>  TI DAVINCI MACHINE SUPPORT
>  M:	Sekhar Nori <nsekhar@ti.com>
>  R:	Bartosz Golaszewski <brgl@bgdev.pl>
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index 9fbdba0fd1e7..0fa58563d93b 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -216,6 +216,18 @@ config VIDEO_RCAR_ISP
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called rcar-isp.
>  
> +config VIDEO_TI_J721E_CSI2RX
> +	tristate "TI J721E CSI2RX wrapper layer driver"
> +	depends on VIDEO_DEV && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
> +	depends on MEDIA_SUPPORT && MEDIA_CONTROLLER
> +	depends on PHY_CADENCE_DPHY_RX && VIDEO_CADENCE_CSI2RX
> +	depends on ARCH_K3 || COMPILE_TEST
> +	select VIDEOBUF2_DMA_CONTIG
> +	select V4L2_FWNODE
> +	help
> +	  Support for TI CSI2RX wrapper layer. This just enables the wrapper driver.
> +	  The Cadence CSI2RX bridge driver needs to be enabled separately.
> +
>  endif # V4L_PLATFORM_DRIVERS
>  
>  menuconfig V4L_MEM2MEM_DRIVERS
> diff --git a/drivers/media/platform/ti/Makefile b/drivers/media/platform/ti/Makefile
> index bbc737ccbbea..17c9cfb74f66 100644
> --- a/drivers/media/platform/ti/Makefile
> +++ b/drivers/media/platform/ti/Makefile
> @@ -1,3 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-y += cal/
>  obj-y += vpe/
> +obj-y += j721e-csi2rx/

Alphabetical order maybe ?

> diff --git a/drivers/media/platform/ti/j721e-csi2rx/Makefile b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> new file mode 100644
> index 000000000000..377afc1d6280
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_VIDEO_TI_J721E_CSI2RX) += j721e-csi2rx.o
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> new file mode 100644
> index 000000000000..43f31f161f43
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -0,0 +1,913 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * TI CSI2 RX driver.
> + *
> + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
> + *
> + * Author: Pratyush Yadav <p.yadav@ti.com>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/dmaengine.h>
> +#include <linux/of_platform.h>

Alphabetical order would be nice here too.

> +
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-ioctl.h>
> +#include <media/videobuf2-dma-contig.h>
> +
> +#define TI_CSI2RX_MODULE_NAME		"j721e-csi2rx"
> +
> +#define SHIM_CNTL			0x10
> +#define SHIM_CNTL_PIX_RST		BIT(0)
> +
> +#define SHIM_DMACNTX			0x20
> +#define SHIM_DMACNTX_EN			BIT(31)
> +#define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
> +#define SHIM_DMACNTX_FMT		GENMASK(5, 0)
> +#define SHIM_DMACNTX_UYVY		0
> +#define SHIM_DMACNTX_VYUY		1
> +#define SHIM_DMACNTX_YUYV		2
> +#define SHIM_DMACNTX_YVYU		3
> +
> +#define SHIM_PSI_CFG0			0x24
> +#define SHIM_PSI_CFG0_SRC_TAG		GENMASK(15, 0)
> +#define SHIM_PSI_CFG0_DST_TAG		GENMASK(31, 15)
> +
> +#define CSI_DF_YUV420			0x18
> +#define CSI_DF_YUV422			0x1e
> +#define CSI_DF_RGB444			0x20
> +#define CSI_DF_RGB888			0x24

https://lore.kernel.org/linux-media/20220123160857.24161-2-laurent.pinchart+renesas@ideasonboard.com/

:-)

> +
> +#define PSIL_WORD_SIZE_BYTES		16
> +/*
> + * There are no hard limits on the width or height. The DMA engine can handle
> + * all sizes. The max width and height are arbitrary numbers for this driver.
> + * Use 16M * 16M as the arbitrary limit. It is large enough that it is unlikely
> + * the limit will be hit in practice.
> + */
> +#define MAX_WIDTH_BYTES			SZ_16M
> +#define MAX_HEIGHT_BYTES		SZ_16M
> +
> +struct ti_csi2rx_fmt {
> +	u32				fourcc;	/* Four character code. */
> +	u32				code;	/* Mbus code. */
> +	enum v4l2_colorspace		colorspace;
> +	u32				csi_df;	/* CSI Data format. */

It's called data type in CSI-2, not data format.

> +	u8				bpp;	/* Bits per pixel. */
> +};
> +
> +struct ti_csi2rx_buffer {
> +	/* Common v4l2 buffer. Must be first. */
> +	struct vb2_v4l2_buffer		vb;
> +	struct list_head		list;
> +	struct ti_csi2rx_dev		*csi;
> +};
> +
> +enum ti_csi2rx_dma_state {
> +	TI_CSI2RX_DMA_STOPPED,	/* Streaming not started yet. */
> +	TI_CSI2RX_DMA_IDLE,	/* Streaming but no pending DMA operation. */
> +	TI_CSI2RX_DMA_ACTIVE,	/* Streaming and pending DMA operation. */
> +};
> +
> +struct ti_csi2rx_dma {
> +	/* Protects all fields in this struct. */
> +	spinlock_t			lock;
> +	struct dma_chan			*chan;
> +	/* Buffers queued to the driver, waiting to be processed by DMA. */
> +	struct list_head		queue;
> +	enum ti_csi2rx_dma_state	state;
> +	/*
> +	 * Current buffer being processed by DMA. NULL if no buffer is being
> +	 * processed.
> +	 */
> +	struct ti_csi2rx_buffer		*curr;
> +};
> +
> +struct ti_csi2rx_dev {
> +	struct device			*dev;
> +	void __iomem			*shim;
> +	struct v4l2_device		v4l2_dev;
> +	struct video_device		vdev;
> +	struct media_device		mdev;
> +	struct media_pipeline		pipe;
> +	struct media_pad		pad;
> +	struct v4l2_async_notifier	notifier;
> +	struct v4l2_subdev		*subdev;
> +	struct vb2_queue		vidq;
> +	struct mutex			mutex; /* To serialize ioctls. */
> +	struct v4l2_format		v_fmt;
> +	struct ti_csi2rx_dma		dma;
> +	u32				sequence;
> +};
> +
> +static const struct ti_csi2rx_fmt formats[] = {
> +	{
> +		.fourcc			= V4L2_PIX_FMT_YUYV,
> +		.code			= MEDIA_BUS_FMT_YUYV8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_UYVY,
> +		.code			= MEDIA_BUS_FMT_UYVY8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_YVYU,
> +		.code			= MEDIA_BUS_FMT_YVYU8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_VYUY,
> +		.code			= MEDIA_BUS_FMT_VYUY8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	},
> +
> +	/* More formats can be supported but they are not listed for now. */
> +};
> +
> +static const unsigned int num_formats = ARRAY_SIZE(formats);
> +
> +/* Forward declaration needed by ti_csi2rx_dma_callback. */
> +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> +			       struct ti_csi2rx_buffer *buf);
> +
> +static const struct ti_csi2rx_fmt *find_format_by_pix(u32 pixelformat)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < num_formats; i++) {
> +		if (formats[i].fourcc == pixelformat)
> +			return &formats[i];
> +	}
> +
> +	return NULL;
> +}
> +
> +static void ti_csi2rx_fill_fmt(const struct ti_csi2rx_fmt *csi_fmt,
> +			       struct v4l2_format *v4l2_fmt)
> +{
> +	struct v4l2_pix_format *pix = &v4l2_fmt->fmt.pix;
> +	u32 bpl;
> +
> +	v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	pix->pixelformat = csi_fmt->fourcc;
> +	pix->colorspace = csi_fmt->colorspace;

I'd drop this (and the colorspace field in ti_csi2rx_fmt). This driver
doesn't care about colorspaces, it should accept any value set by
userspace, which should match the colorspace produced by the source
subdev.

ti_csi2rx_v4l2_init() will have to set a default colorspace explicitly.

> +	pix->sizeimage = pix->height * pix->width * (csi_fmt->bpp / 8);
> +
> +	bpl = (pix->width * ALIGN(csi_fmt->bpp, 8)) >> 3;
> +	pix->bytesperline = ALIGN(bpl, 16);
> +}
> +
> +static int ti_csi2rx_querycap(struct file *file, void *priv,
> +			      struct v4l2_capability *cap)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +
> +	strscpy(cap->driver, TI_CSI2RX_MODULE_NAME, sizeof(cap->driver));
> +	strscpy(cap->card, TI_CSI2RX_MODULE_NAME, sizeof(cap->card));
> +
> +	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
> +		 dev_name(csi->dev));

Depending on which series gets merged, you can drop this line:

https://lore.kernel.org/linux-media/20220122163656.168440-1-sakari.ailus@linux.intel.com/

> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_fmt_vid_cap(struct file *file, void *priv,
> +				      struct v4l2_fmtdesc *f)
> +{
> +	if (f->index >= num_formats)
> +		return -EINVAL;
> +
> +	memset(f->reserved, 0, sizeof(f->reserved));
> +	f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	f->pixelformat = formats[f->index].fourcc;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_g_fmt_vid_cap(struct file *file, void *prov,
> +				   struct v4l2_format *f)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +
> +	*f = csi->v_fmt;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_try_fmt_vid_cap(struct file *file, void *priv,
> +				     struct v4l2_format *f)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +
> +	/*
> +	 * Default to the first format if the requested pixel format code isn't
> +	 * supported.
> +	 */
> +	fmt = find_format_by_pix(f->fmt.pix.pixelformat);
> +	if (!fmt)
> +		fmt = &formats[0];
> +
> +	if (f->fmt.pix.field == V4L2_FIELD_ANY)
> +		f->fmt.pix.field = V4L2_FIELD_NONE;
> +
> +	if (f->fmt.pix.field != V4L2_FIELD_NONE)
> +		return -EINVAL;

You should adjust the field, not return an error, so this can just
become

	/* Interlaced formats are not supported. */
	f->fmt.pix.field = V4L2_FIELD_NONE;

> +
> +	ti_csi2rx_fill_fmt(fmt, f);
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_s_fmt_vid_cap(struct file *file, void *priv,
> +				   struct v4l2_format *f)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +	struct vb2_queue *q = &csi->vidq;
> +	int ret;
> +
> +	if (vb2_is_busy(q))
> +		return -EBUSY;
> +
> +	ret = ti_csi2rx_try_fmt_vid_cap(file, priv, f);
> +	if (ret < 0)
> +		return ret;
> +
> +	csi->v_fmt = *f;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_framesizes(struct file *file, void *fh,
> +				     struct v4l2_frmsizeenum *fsize)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +	unsigned int pixels_in_word;
> +	u8 bpp;
> +
> +	fmt = find_format_by_pix(fsize->pixel_format);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	bpp = ALIGN(fmt->bpp, 8);
> +
> +	/*
> +	 * Number of pixels in one PSI-L word. The transfer happens in multiples
> +	 * of PSI-L word sizes.
> +	 */
> +	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> +
> +	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
> +	fsize->stepwise.min_width = pixels_in_word;
> +	fsize->stepwise.max_width = rounddown(MAX_WIDTH_BYTES, pixels_in_word);
> +	fsize->stepwise.step_width = pixels_in_word;
> +	fsize->stepwise.min_height = 1;
> +	fsize->stepwise.max_height = MAX_HEIGHT_BYTES;
> +	fsize->stepwise.step_height = 1;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ioctl_ops csi_ioctl_ops = {
> +	.vidioc_querycap      = ti_csi2rx_querycap,
> +	.vidioc_enum_fmt_vid_cap = ti_csi2rx_enum_fmt_vid_cap,
> +	.vidioc_try_fmt_vid_cap = ti_csi2rx_try_fmt_vid_cap,
> +	.vidioc_g_fmt_vid_cap = ti_csi2rx_g_fmt_vid_cap,
> +	.vidioc_s_fmt_vid_cap = ti_csi2rx_s_fmt_vid_cap,
> +	.vidioc_enum_framesizes = ti_csi2rx_enum_framesizes,
> +	.vidioc_reqbufs       = vb2_ioctl_reqbufs,
> +	.vidioc_create_bufs   = vb2_ioctl_create_bufs,
> +	.vidioc_prepare_buf   = vb2_ioctl_prepare_buf,
> +	.vidioc_querybuf      = vb2_ioctl_querybuf,
> +	.vidioc_qbuf          = vb2_ioctl_qbuf,
> +	.vidioc_dqbuf         = vb2_ioctl_dqbuf,
> +	.vidioc_expbuf        = vb2_ioctl_expbuf,
> +	.vidioc_streamon      = vb2_ioctl_streamon,
> +	.vidioc_streamoff     = vb2_ioctl_streamoff,
> +};
> +
> +static const struct v4l2_file_operations csi_fops = {
> +	.owner = THIS_MODULE,
> +	.open = v4l2_fh_open,
> +	.release = vb2_fop_release,
> +	.read = vb2_fop_read,
> +	.poll = vb2_fop_poll,
> +	.unlocked_ioctl = video_ioctl2,
> +	.mmap = vb2_fop_mmap,
> +};
> +
> +static int ti_csi2rx_video_register(struct ti_csi2rx_dev *csi)
> +{
> +	struct video_device *vdev = &csi->vdev;
> +	int ret, src_pad;
> +
> +	ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> +	if (ret)
> +		return ret;
> +
> +	src_pad = media_entity_get_fwnode_pad(&csi->subdev->entity,
> +					      csi->subdev->fwnode,
> +					      MEDIA_PAD_FL_SOURCE);
> +	if (src_pad < 0) {
> +		dev_err(csi->dev, "Couldn't find source pad for subdev\n");
> +		return src_pad;
> +	}
> +
> +	ret = media_create_pad_link(&csi->subdev->entity, src_pad,
> +				    &vdev->entity, 0,
> +				    MEDIA_LNK_FL_IMMUTABLE |
> +				    MEDIA_LNK_FL_ENABLED);
> +	if (ret) {
> +		video_unregister_device(vdev);
> +		return ret;
> +	}

This can be simplified by using v4l2_create_fwnode_links_to_pad().

> +
> +	return 0;
> +}
> +
> +static int csi_async_notifier_bound(struct v4l2_async_notifier *notifier,
> +				    struct v4l2_subdev *subdev,
> +				    struct v4l2_async_subdev *asd)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +
> +	csi->subdev = subdev;
> +
> +	return 0;
> +}
> +
> +static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +	int ret;
> +
> +	ret = ti_csi2rx_video_register(csi);

I would inline the ti_csi2rx_video_register() function here, it's not
large, and it's only called in a single place.

> +	if (ret)
> +		return ret;
> +
> +	return v4l2_device_register_subdev_nodes(&csi->v4l2_dev);
> +}
> +
> +static const struct v4l2_async_notifier_operations csi_async_notifier_ops = {
> +	.bound = csi_async_notifier_bound,
> +	.complete = csi_async_notifier_complete,
> +};
> +
> +static int ti_csi2rx_init_subdev(struct ti_csi2rx_dev *csi)
> +{
> +	struct fwnode_handle *fwnode;
> +	struct v4l2_async_subdev *asd;
> +	struct device_node *node;
> +	int ret;
> +
> +	node = of_get_child_by_name(csi->dev->of_node, "csi-bridge");
> +	if (!node)
> +		return -EINVAL;
> +
> +	fwnode = of_fwnode_handle(node);
> +	if (!fwnode) {
> +		of_node_put(node);
> +		return -EINVAL;
> +	}
> +
> +	v4l2_async_nf_init(&csi->notifier);
> +	csi->notifier.ops = &csi_async_notifier_ops;
> +
> +	asd = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> +				       struct v4l2_async_subdev);
> +	of_node_put(node);
> +	if (IS_ERR(asd)) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return PTR_ERR(asd);
> +	}
> +
> +	ret = v4l2_async_nf_register(&csi->v4l2_dev, &csi->notifier);
> +	if (ret) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_setup_shim(struct ti_csi2rx_dev *csi)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +	unsigned int reg;
> +
> +	fmt = find_format_by_pix(csi->v_fmt.fmt.pix.pixelformat);
> +	if (!fmt) {
> +		dev_err(csi->dev, "Unknown format\n");
> +		return;
> +	}
> +
> +	/* De-assert the pixel interface reset. */
> +	reg = SHIM_CNTL_PIX_RST;
> +	writel(reg, csi->shim + SHIM_CNTL);
> +
> +	reg = SHIM_DMACNTX_EN;
> +	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_df);
> +
> +	/*
> +	 * Using the values from the documentation gives incorrect ordering for
> +	 * the luma and chroma components. In practice, the "reverse" format
> +	 * gives the correct image. So for example, if the image is in UYVY, the
> +	 * reverse would be YVYU.

Are you sure this is an issue in the documentation, not in the
implementation of the source subdev ?

> +	 */
> +	switch (fmt->fourcc) {
> +	case V4L2_PIX_FMT_UYVY:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_YVYU);
> +		break;
> +	case V4L2_PIX_FMT_VYUY:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_YUYV);
> +		break;
> +	case V4L2_PIX_FMT_YUYV:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_VYUY);
> +		break;
> +	case V4L2_PIX_FMT_YVYU:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_UYVY);
> +		break;
> +	default:
> +		/* Ignore if not YUV 4:2:2 */
> +		break;
> +	}
> +
> +	writel(reg, csi->shim + SHIM_DMACNTX);
> +
> +	reg = FIELD_PREP(SHIM_PSI_CFG0_SRC_TAG, 0) |
> +	      FIELD_PREP(SHIM_PSI_CFG0_DST_TAG, 1);
> +	writel(reg, csi->shim + SHIM_PSI_CFG0);
> +}
> +
> +static void ti_csi2rx_dma_callback(void *param)
> +{
> +	struct ti_csi2rx_buffer *buf = param;
> +	struct ti_csi2rx_dev *csi = buf->csi;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags = 0;

No need to initialize flags to 0.

> +
> +	buf->vb.vb2_buf.timestamp = ktime_get_ns();
> +	buf->vb.sequence = csi->sequence++;

Is there any hardware frame counter that could be used, to detect
dropped frames ? Or maybe a SOF hardware interrupt somewhere (either in
the SHIM or the CSI-2 receiver) ?

> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +
> +	WARN_ON(dma->curr != buf);
> +	vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> +
> +	/* If there are more buffers to process then start their transfer. */
> +	dma->curr = NULL;
> +	while (!list_empty(&dma->queue)) {
> +		buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +		list_del(&buf->list);
> +
> +		if (ti_csi2rx_start_dma(csi, buf)) {
> +			dev_err(csi->dev, "Failed to queue the next buffer for DMA\n");
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);

If this buffer fails to be queued, do you expect that the next buffer in
the list would succeed ? It seems to be a fatal error to me.

> +		} else {
> +			dma->curr = buf;
> +			break;

Shouldn't all pending buffers be queued to the DMA engine ? It seems
that you're queuing one buffer at a time, which would cause an underrun
if the system is too slow to queue the next buffer during vertical
blanking. It defeats the point of having multiple buffers in the V4L2
queue. You should instead queue the buffers to the DMA engine as soon as
they're received by the driver.

> +		}
> +	}
> +
> +	if (!dma->curr)
> +		dma->state = TI_CSI2RX_DMA_IDLE;
> +
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> +			       struct ti_csi2rx_buffer *buf)
> +{
> +	unsigned long addr;
> +	struct dma_async_tx_descriptor *desc;
> +	size_t len = csi->v_fmt.fmt.pix.sizeimage;
> +	dma_cookie_t cookie;
> +	int ret = 0;
> +
> +	addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> +	desc = dmaengine_prep_slave_single(csi->dma.chan, addr, len,
> +					   DMA_DEV_TO_MEM,
> +					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc)
> +		return -EIO;
> +
> +	desc->callback = ti_csi2rx_dma_callback;
> +	desc->callback_param = buf;
> +
> +	cookie = dmaengine_submit(desc);
> +	ret = dma_submit_error(cookie);
> +	if (ret)
> +		return ret;
> +
> +	dma_async_issue_pending(csi->dma.chan);
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_queue_setup(struct vb2_queue *q, unsigned int *nbuffers,
> +				 unsigned int *nplanes, unsigned int sizes[],
> +				 struct device *alloc_devs[])
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(q);
> +	unsigned int size = csi->v_fmt.fmt.pix.sizeimage;
> +
> +	if (*nplanes) {
> +		if (sizes[0] < size)
> +			return -EINVAL;
> +		size = sizes[0];
> +	}
> +
> +	*nplanes = 1;
> +	sizes[0] = size;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_buffer_prepare(struct vb2_buffer *vb)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> +	unsigned long size = csi->v_fmt.fmt.pix.sizeimage;
> +
> +	if (vb2_plane_size(vb, 0) < size) {
> +		dev_err(csi->dev, "Data will not fit into plane\n");
> +		return -EINVAL;
> +	}
> +
> +	vb2_set_plane_payload(vb, 0, size);
> +	return 0;
> +}
> +
> +static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> +	struct ti_csi2rx_buffer *buf;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags = 0;
> +	int ret;
> +
> +	buf = container_of(vb, struct ti_csi2rx_buffer, vb.vb2_buf);
> +	buf->csi = csi;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	/*
> +	 * Usually the DMA callback takes care of queueing the pending buffers.
> +	 * But if DMA has stalled due to lack of buffers, restart it now.
> +	 */
> +	if (dma->state == TI_CSI2RX_DMA_IDLE) {
> +		ret = ti_csi2rx_start_dma(csi, buf);
> +		if (ret) {
> +			dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +			goto unlock;
> +		}
> +
> +		dma->curr = buf;
> +		dma->state = TI_CSI2RX_DMA_ACTIVE;
> +	} else {
> +		list_add_tail(&buf->list, &dma->queue);
> +	}
> +
> +unlock:
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	struct ti_csi2rx_buffer *buf, *tmp;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	if (list_empty(&dma->queue))
> +		ret = -EIO;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +	if (ret)
> +		return ret;
> +
> +	ret = media_pipeline_start(&csi->vdev.entity, &csi->pipe);
> +	if (ret)
> +		goto err;
> +
> +	ti_csi2rx_setup_shim(csi);
> +
> +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 1);
> +	if (ret)
> +		goto err_pipeline;
> +
> +	csi->sequence = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +	list_del(&buf->list);
> +	dma->state = TI_CSI2RX_DMA_ACTIVE;
> +
> +	ret = ti_csi2rx_start_dma(csi, buf);

Shouldn't you start DMA before starting the source subdev ? You may miss
the first frame otherwise.

> +	if (ret) {
> +		dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +		spin_unlock_irqrestore(&dma->lock, flags);
> +		goto err_stream;
> +	}
> +
> +	dma->curr = buf;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	return 0;
> +
> +err_stream:
> +	v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> +err_pipeline:
> +	media_pipeline_stop(&csi->vdev.entity);
> +err:
> +	spin_lock_irqsave(&dma->lock, flags);
> +	list_for_each_entry_safe(buf, tmp, &dma->queue, list) {
> +		list_del(&buf->list);
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +	}
> +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	return ret;
> +}
> +
> +static void ti_csi2rx_stop_streaming(struct vb2_queue *vq)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	struct ti_csi2rx_buffer *buf = NULL, *tmp;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags = 0;
> +	int ret;
> +
> +	media_pipeline_stop(&csi->vdev.entity);
> +
> +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop subdev stream\n");
> +
> +	writel(0, csi->shim + SHIM_CNTL);
> +
> +	ret = dmaengine_terminate_sync(csi->dma.chan);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop DMA\n");
> +
> +	writel(0, csi->shim + SHIM_DMACNTX);
> +

Code from here...

> +	spin_lock_irqsave(&dma->lock, flags);
> +	list_for_each_entry_safe(buf, tmp, &csi->dma.queue, list) {
> +		list_del(&buf->list);
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +	}
> +
> +	if (dma->curr)
> +		vb2_buffer_done(&dma->curr->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +
> +	dma->curr = NULL;

... to here could be moved to a separate function that takes a VB2 buf
state parameter, to be also used in the error path of
ti_csi2rx_start_streaming().

> +	dma->state = TI_CSI2RX_DMA_STOPPED;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static const struct vb2_ops csi_vb2_qops = {
> +	.queue_setup = ti_csi2rx_queue_setup,
> +	.buf_prepare = ti_csi2rx_buffer_prepare,
> +	.buf_queue = ti_csi2rx_buffer_queue,
> +	.start_streaming = ti_csi2rx_start_streaming,
> +	.stop_streaming = ti_csi2rx_stop_streaming,
> +	.wait_prepare = vb2_ops_wait_prepare,
> +	.wait_finish = vb2_ops_wait_finish,
> +};
> +
> +static int ti_csi2rx_init_vb2q(struct ti_csi2rx_dev *csi)
> +{
> +	struct vb2_queue *q = &csi->vidq;
> +	int ret;
> +
> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	q->io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF | VB2_READ;

Usage of USERPTR and READ is not recommended, I'd drop them from the
driver.

> +	q->drv_priv = csi;
> +	q->buf_struct_size = sizeof(struct ti_csi2rx_buffer);
> +	q->ops = &csi_vb2_qops;
> +	q->mem_ops = &vb2_dma_contig_memops;
> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	q->dev = dmaengine_get_dma_device(csi->dma.chan);

That's interesting, why do you use the dmaengine device and not csi->dev
?

> +	q->lock = &csi->mutex;
> +
> +	ret = vb2_queue_init(q);
> +	if (ret)
> +		return ret;
> +
> +	csi->vdev.queue = q;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_init_dma(struct ti_csi2rx_dev *csi)
> +{
> +	struct dma_slave_config cfg;

	struct dma_slave_config cfg = { };

and you can drop the memset below. Or possibly even better,

	struct dma_slave_config cfg = {
		.src_addr_with = DMA_SLAVE_BUSWIDTH_16_BYTES,
	};

> +	int ret;
> +
> +	INIT_LIST_HEAD(&csi->dma.queue);
> +	spin_lock_init(&csi->dma.lock);
> +
> +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> +
> +	csi->dma.chan = dma_request_chan(csi->dev, "rx0");
> +	if (IS_ERR(csi->dma.chan))
> +		return PTR_ERR(csi->dma.chan);
> +
> +	memset(&cfg, 0, sizeof(cfg));
> +
> +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_16_BYTES;
> +
> +	ret = dmaengine_slave_config(csi->dma.chan, &cfg);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
> +{
> +	struct media_device *mdev = &csi->mdev;
> +	struct video_device *vdev = &csi->vdev;
> +	const struct ti_csi2rx_fmt *fmt;
> +	struct v4l2_pix_format *pix_fmt = &csi->v_fmt.fmt.pix;
> +	int ret;
> +
> +	fmt = find_format_by_pix(V4L2_PIX_FMT_UYVY);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	pix_fmt->width = 640;
> +	pix_fmt->height = 480;

Should you initialize ->field too ?

> +
> +	ti_csi2rx_fill_fmt(fmt, &csi->v_fmt);
> +
> +	mdev->dev = csi->dev;
> +	mdev->hw_revision = 1;
> +	strscpy(mdev->model, "TI-CSI2RX", sizeof(mdev->model));
> +	snprintf(mdev->bus_info, sizeof(mdev->bus_info), "platform:%s",
> +		 dev_name(mdev->dev));
> +
> +	media_device_init(mdev);
> +
> +	strscpy(vdev->name, TI_CSI2RX_MODULE_NAME, sizeof(vdev->name));
> +	vdev->v4l2_dev = &csi->v4l2_dev;
> +	vdev->vfl_dir = VFL_DIR_RX;
> +	vdev->fops = &csi_fops;
> +	vdev->ioctl_ops = &csi_ioctl_ops;
> +	vdev->release = video_device_release_empty;
> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_READWRITE |

You can also drop V4L2_CAP_READWRITE if you drop VB2_READ above.

> +			    V4L2_CAP_STREAMING | V4L2_CAP_IO_MC;
> +	vdev->lock = &csi->mutex;
> +	video_set_drvdata(vdev, csi);
> +
> +	csi->pad.flags = MEDIA_PAD_FL_SINK;
> +	ret = media_entity_pads_init(&csi->vdev.entity, 1, &csi->pad);
> +	if (ret)
> +		return ret;
> +
> +	csi->v4l2_dev.mdev = mdev;
> +
> +	ret = v4l2_device_register(csi->dev, &csi->v4l2_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = media_device_register(mdev);
> +	if (ret) {
> +		v4l2_device_unregister(&csi->v4l2_dev);
> +		media_device_cleanup(mdev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_cleanup_dma(struct ti_csi2rx_dev *csi)
> +{
> +	dma_release_channel(csi->dma.chan);
> +}
> +
> +static void ti_csi2rx_cleanup_v4l2(struct ti_csi2rx_dev *csi)
> +{
> +	media_device_unregister(&csi->mdev);
> +	v4l2_device_unregister(&csi->v4l2_dev);
> +	media_device_cleanup(&csi->mdev);
> +}
> +
> +static void ti_csi2rx_cleanup_subdev(struct ti_csi2rx_dev *csi)
> +{
> +	v4l2_async_nf_unregister(&csi->notifier);
> +	v4l2_async_nf_cleanup(&csi->notifier);
> +}
> +
> +static void ti_csi2rx_cleanup_vb2q(struct ti_csi2rx_dev *csi)
> +{
> +	vb2_queue_release(&csi->vidq);
> +}
> +
> +static int ti_csi2rx_probe(struct platform_device *pdev)
> +{
> +	struct ti_csi2rx_dev *csi;
> +	struct resource *res;
> +	int ret;
> +
> +	csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);

Don't use devm_kzalloc() here (see the explanation in the remove
function).

> +	if (!csi)
> +		return -ENOMEM;
> +
> +	csi->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, csi);
> +
> +	mutex_init(&csi->mutex);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	csi->shim = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(csi->shim))
> +		return PTR_ERR(csi->shim);
> +
> +	ret = ti_csi2rx_init_dma(csi);
> +	if (ret)
> +		return ret;
> +
> +	ret = ti_csi2rx_v4l2_init(csi);
> +	if (ret)
> +		goto err_dma;
> +
> +	ret = ti_csi2rx_init_vb2q(csi);
> +	if (ret)
> +		goto err_v4l2;
> +
> +	ret = ti_csi2rx_init_subdev(csi);
> +	if (ret)
> +		goto err_vb2q;
> +
> +	ret = of_platform_populate(csi->dev->of_node, NULL, NULL, csi->dev);
> +	if (ret) {
> +		dev_err(csi->dev, "Failed to create children: %d\n", ret);
> +		goto err_subdev;
> +	}
> +
> +	return 0;
> +
> +err_subdev:
> +	ti_csi2rx_cleanup_subdev(csi);
> +err_vb2q:
> +	ti_csi2rx_cleanup_vb2q(csi);
> +err_v4l2:
> +	ti_csi2rx_cleanup_v4l2(csi);
> +err_dma:
> +	ti_csi2rx_cleanup_dma(csi);
> +	return ret;
> +}
> +
> +static int ti_csi2rx_remove(struct platform_device *pdev)
> +{
> +	struct ti_csi2rx_dev *csi = platform_get_drvdata(pdev);
> +
> +	if (vb2_is_busy(&csi->vidq))
> +		return -EBUSY;

That's not right, capture should instead be stopped.

The right way to handle this is to call all the unregister functions
here, but not the cleanup functions, and to implement a real
vdev->release handler that will perform all the cleanup and kfree() the
ti_csi2rx_dev.

> +
> +	video_unregister_device(&csi->vdev);
> +
> +	ti_csi2rx_cleanup_vb2q(csi);
> +	ti_csi2rx_cleanup_subdev(csi);
> +	ti_csi2rx_cleanup_v4l2(csi);
> +	ti_csi2rx_cleanup_dma(csi);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ti_csi2rx_of_match[] = {
> +	{ .compatible = "ti,j721e-csi2rx", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ti_csi2rx_of_match);
> +
> +static struct platform_driver ti_csi2rx_pdrv = {
> +	.probe = ti_csi2rx_probe,
> +	.remove = ti_csi2rx_remove,
> +	.driver = {
> +		.name = TI_CSI2RX_MODULE_NAME,
> +		.of_match_table = ti_csi2rx_of_match,
> +	},
> +};
> +
> +module_platform_driver(ti_csi2rx_pdrv);
> +
> +MODULE_DESCRIPTION("TI J721E CSI2 RX Driver");
> +MODULE_AUTHOR("Pratyush Yadav <p.yadav@ti.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION("1.0");

I'd drop the version, it will never change, so it's quite pointless. If
userspace needs to know if the driver implements a particular feature or
includes a bug fix, it can use the kernel version.

Hi Pratyush,

On Fri, Jan 21, 2022 at 07:59:01PM +0530, Pratyush Yadav wrote:
> TI's J721E uses the Cadence CSI2RX and DPHY peripherals to facilitate
> capture over a CSI-2 bus.
> 
> The Cadence CSI2RX IP acts as a bridge between the TI specific parts and
> the CSI-2 protocol parts. TI then has a wrapper on top of this bridge
> called the SHIM layer. It takes in data from stream 0, repacks it, and
> sends it to memory over PSI-L DMA.
> 
> This driver acts as the "front end" to V4L2 client applications. It
> implements the required ioctls and buffer operations, passes the
> necessary calls on to the bridge, programs the SHIM layer, and performs
> DMA via the dmaengine API to finally return the data to a buffer
> supplied by the application.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> 
> ---
> 
> (no changes since v5)
> 
> Changes in v5:
> - Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
>   since the Rx mode DPHY now has a separate driver.
> - Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be done
>   at media_pipeline_start().
> - Do not assign flags.
> - Fix error handling in ti_csi2rx_start_streaming(). Free up vb2 buffers
>   when media_pipeline_start() fails.
> 
> Changes in v4:
> - Acquire the media device's graph_mutex before starting the graph walk.
> - Call media_graph_walk_init() and media_graph_walk_cleanup() when
>   starting and ending the graph walk respectively.
> - Reduce max frame height and width in enum_framesizes. Currently they
>   are set to UINT_MAX but they must be a multiple of step_width, so they
>   need to be rounded down. Also, these values are absurdly large which
>   causes some userspace applications like gstreamer to trip up. While it
>   is not generally right to change the kernel for an application bug, it
>   is not such a big deal here. This change is replacing one set of
>   absurdly large arbitrary values with another set of smaller but still
>   absurdly large arbitrary values. Both limits are unlikely to be hit in
>   practice.
> 
> Changes in v3:
> - Move DMA related fields in struct ti_csi2rx_dma.
> - Protect DMA buffer queue with a spinlock to make sure the queue buffer
>   and DMA callback don't race on it.
> - Track the current DMA state. It might go idle because of a lack of
>   buffers. This state can be used to restart it if needed.
> - Do not include the current buffer in the pending queue. It is slightly
>   better modelling than leaving it at the head of the pending queue.
> - Use the buffer as the callback argument, and add a reference to csi in it.
> - If queueing a buffer to DMA fails, the buffer gets leaked and DMA gets
>   stalled with. Instead, report the error to vb2 and queue the next
>   buffer in the pending queue.
> - DMA gets stalled if we run out of buffers since the callback is the
>   only one that fires subsequent transfers and it is no longer being
>   called. Check for that when queueing buffers and restart DMA if
>   needed.
> - Do not put of node until we are done using the fwnode.
> - Set inital format to UYVY 640x480.
> 
> Changes in v2:
> - Use dmaengine_get_dma_device() instead of directly accessing
>   dma->device->dev.
> - Do not set dst_addr_width when configuring slave DMA.
> - Move to a separate subdir and rename to j721e-csi2rx.c
> - Convert compatible to ti,j721e-csi2rx.
> - Move to use Media Controller centric APIs.
> - Improve cleanup in probe when one of the steps fails.
> - Add colorspace to formats database.
> - Set hw_revision on media_device.
> - Move video device initialization to probe time instead of register time.
> 
>  MAINTAINERS                                   |   6 +
>  drivers/media/platform/Kconfig                |  12 +
>  drivers/media/platform/ti/Makefile            |   1 +
>  .../media/platform/ti/j721e-csi2rx/Makefile   |   2 +
>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 913 ++++++++++++++++++
>  5 files changed, 934 insertions(+)
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3b8fa4e5047f..2a8ebf17462e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19181,6 +19181,12 @@ S:	Odd Fixes
>  F:	drivers/clk/ti/
>  F:	include/linux/clk/ti.h
>  
> +TI J721E CSI2RX DRIVER
> +M:	Pratyush Yadav <p.yadav@ti.com>
> +L:	linux-media@vger.kernel.org
> +S:	Supported
> +F:	drivers/media/platform/ti/j721e-csi2rx/
> +
>  TI DAVINCI MACHINE SUPPORT
>  M:	Sekhar Nori <nsekhar@ti.com>
>  R:	Bartosz Golaszewski <brgl@bgdev.pl>
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index 9fbdba0fd1e7..0fa58563d93b 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -216,6 +216,18 @@ config VIDEO_RCAR_ISP
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called rcar-isp.
>  
> +config VIDEO_TI_J721E_CSI2RX
> +	tristate "TI J721E CSI2RX wrapper layer driver"
> +	depends on VIDEO_DEV && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
> +	depends on MEDIA_SUPPORT && MEDIA_CONTROLLER
> +	depends on PHY_CADENCE_DPHY_RX && VIDEO_CADENCE_CSI2RX
> +	depends on ARCH_K3 || COMPILE_TEST
> +	select VIDEOBUF2_DMA_CONTIG
> +	select V4L2_FWNODE
> +	help
> +	  Support for TI CSI2RX wrapper layer. This just enables the wrapper driver.
> +	  The Cadence CSI2RX bridge driver needs to be enabled separately.
> +
>  endif # V4L_PLATFORM_DRIVERS
>  
>  menuconfig V4L_MEM2MEM_DRIVERS
> diff --git a/drivers/media/platform/ti/Makefile b/drivers/media/platform/ti/Makefile
> index bbc737ccbbea..17c9cfb74f66 100644
> --- a/drivers/media/platform/ti/Makefile
> +++ b/drivers/media/platform/ti/Makefile
> @@ -1,3 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-y += cal/
>  obj-y += vpe/
> +obj-y += j721e-csi2rx/
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/Makefile b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> new file mode 100644
> index 000000000000..377afc1d6280
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_VIDEO_TI_J721E_CSI2RX) += j721e-csi2rx.o
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> new file mode 100644
> index 000000000000..43f31f161f43
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -0,0 +1,913 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * TI CSI2 RX driver.
> + *
> + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
> + *
> + * Author: Pratyush Yadav <p.yadav@ti.com>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/dmaengine.h>
> +#include <linux/of_platform.h>
> +
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-ioctl.h>
> +#include <media/videobuf2-dma-contig.h>
> +
> +#define TI_CSI2RX_MODULE_NAME		"j721e-csi2rx"
> +
> +#define SHIM_CNTL			0x10
> +#define SHIM_CNTL_PIX_RST		BIT(0)
> +
> +#define SHIM_DMACNTX			0x20
> +#define SHIM_DMACNTX_EN			BIT(31)
> +#define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
> +#define SHIM_DMACNTX_FMT		GENMASK(5, 0)
> +#define SHIM_DMACNTX_UYVY		0
> +#define SHIM_DMACNTX_VYUY		1
> +#define SHIM_DMACNTX_YUYV		2
> +#define SHIM_DMACNTX_YVYU		3
> +
> +#define SHIM_PSI_CFG0			0x24
> +#define SHIM_PSI_CFG0_SRC_TAG		GENMASK(15, 0)
> +#define SHIM_PSI_CFG0_DST_TAG		GENMASK(31, 15)
> +
> +#define CSI_DF_YUV420			0x18
> +#define CSI_DF_YUV422			0x1e
> +#define CSI_DF_RGB444			0x20
> +#define CSI_DF_RGB888			0x24
> +
> +#define PSIL_WORD_SIZE_BYTES		16
> +/*
> + * There are no hard limits on the width or height. The DMA engine can handle
> + * all sizes. The max width and height are arbitrary numbers for this driver.
> + * Use 16M * 16M as the arbitrary limit. It is large enough that it is unlikely
> + * the limit will be hit in practice.
> + */
> +#define MAX_WIDTH_BYTES			SZ_16M
> +#define MAX_HEIGHT_BYTES		SZ_16M
> +
> +struct ti_csi2rx_fmt {
> +	u32				fourcc;	/* Four character code. */
> +	u32				code;	/* Mbus code. */
> +	enum v4l2_colorspace		colorspace;
> +	u32				csi_df;	/* CSI Data format. */
> +	u8				bpp;	/* Bits per pixel. */
> +};
> +
> +struct ti_csi2rx_buffer {
> +	/* Common v4l2 buffer. Must be first. */
> +	struct vb2_v4l2_buffer		vb;
> +	struct list_head		list;
> +	struct ti_csi2rx_dev		*csi;
> +};
> +
> +enum ti_csi2rx_dma_state {
> +	TI_CSI2RX_DMA_STOPPED,	/* Streaming not started yet. */
> +	TI_CSI2RX_DMA_IDLE,	/* Streaming but no pending DMA operation. */
> +	TI_CSI2RX_DMA_ACTIVE,	/* Streaming and pending DMA operation. */
> +};
> +
> +struct ti_csi2rx_dma {
> +	/* Protects all fields in this struct. */
> +	spinlock_t			lock;
> +	struct dma_chan			*chan;
> +	/* Buffers queued to the driver, waiting to be processed by DMA. */
> +	struct list_head		queue;
> +	enum ti_csi2rx_dma_state	state;
> +	/*
> +	 * Current buffer being processed by DMA. NULL if no buffer is being
> +	 * processed.
> +	 */
> +	struct ti_csi2rx_buffer		*curr;
> +};
> +
> +struct ti_csi2rx_dev {
> +	struct device			*dev;
> +	void __iomem			*shim;
> +	struct v4l2_device		v4l2_dev;
> +	struct video_device		vdev;
> +	struct media_device		mdev;
> +	struct media_pipeline		pipe;
> +	struct media_pad		pad;
> +	struct v4l2_async_notifier	notifier;
> +	struct v4l2_subdev		*subdev;
> +	struct vb2_queue		vidq;
> +	struct mutex			mutex; /* To serialize ioctls. */
> +	struct v4l2_format		v_fmt;
> +	struct ti_csi2rx_dma		dma;
> +	u32				sequence;
> +};
> +
> +static const struct ti_csi2rx_fmt formats[] = {
> +	{
> +		.fourcc			= V4L2_PIX_FMT_YUYV,
> +		.code			= MEDIA_BUS_FMT_YUYV8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_UYVY,
> +		.code			= MEDIA_BUS_FMT_UYVY8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_YVYU,
> +		.code			= MEDIA_BUS_FMT_YVYU8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_VYUY,
> +		.code			= MEDIA_BUS_FMT_VYUY8_2X8,
> +		.colorspace		= V4L2_COLORSPACE_SRGB,
> +		.csi_df			= CSI_DF_YUV422,
> +		.bpp			= 16,
> +	},
> +
> +	/* More formats can be supported but they are not listed for now. */
> +};
> +
> +static const unsigned int num_formats = ARRAY_SIZE(formats);
> +
> +/* Forward declaration needed by ti_csi2rx_dma_callback. */
> +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> +			       struct ti_csi2rx_buffer *buf);
> +
> +static const struct ti_csi2rx_fmt *find_format_by_pix(u32 pixelformat)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < num_formats; i++) {
> +		if (formats[i].fourcc == pixelformat)
> +			return &formats[i];
> +	}
> +
> +	return NULL;
> +}
> +
> +static void ti_csi2rx_fill_fmt(const struct ti_csi2rx_fmt *csi_fmt,
> +			       struct v4l2_format *v4l2_fmt)
> +{
> +	struct v4l2_pix_format *pix = &v4l2_fmt->fmt.pix;
> +	u32 bpl;
> +
> +	v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	pix->pixelformat = csi_fmt->fourcc;
> +	pix->colorspace = csi_fmt->colorspace;
> +	pix->sizeimage = pix->height * pix->width * (csi_fmt->bpp / 8);

This can overflow.

Width and height also aren't checked for the same limits (including step)
you have in enum_framesizes.

> +
> +	bpl = (pix->width * ALIGN(csi_fmt->bpp, 8)) >> 3;
> +	pix->bytesperline = ALIGN(bpl, 16);
> +}
> +
> +static int ti_csi2rx_querycap(struct file *file, void *priv,
> +			      struct v4l2_capability *cap)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +
> +	strscpy(cap->driver, TI_CSI2RX_MODULE_NAME, sizeof(cap->driver));
> +	strscpy(cap->card, TI_CSI2RX_MODULE_NAME, sizeof(cap->card));
> +
> +	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
> +		 dev_name(csi->dev));
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_fmt_vid_cap(struct file *file, void *priv,
> +				      struct v4l2_fmtdesc *f)
> +{
> +	if (f->index >= num_formats)
> +		return -EINVAL;
> +
> +	memset(f->reserved, 0, sizeof(f->reserved));
> +	f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	f->pixelformat = formats[f->index].fourcc;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_g_fmt_vid_cap(struct file *file, void *prov,
> +				   struct v4l2_format *f)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +
> +	*f = csi->v_fmt;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_try_fmt_vid_cap(struct file *file, void *priv,
> +				     struct v4l2_format *f)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +
> +	/*
> +	 * Default to the first format if the requested pixel format code isn't
> +	 * supported.
> +	 */
> +	fmt = find_format_by_pix(f->fmt.pix.pixelformat);
> +	if (!fmt)
> +		fmt = &formats[0];
> +
> +	if (f->fmt.pix.field == V4L2_FIELD_ANY)
> +		f->fmt.pix.field = V4L2_FIELD_NONE;
> +
> +	if (f->fmt.pix.field != V4L2_FIELD_NONE)
> +		return -EINVAL;
> +
> +	ti_csi2rx_fill_fmt(fmt, f);
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_s_fmt_vid_cap(struct file *file, void *priv,
> +				   struct v4l2_format *f)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +	struct vb2_queue *q = &csi->vidq;
> +	int ret;
> +
> +	if (vb2_is_busy(q))
> +		return -EBUSY;
> +
> +	ret = ti_csi2rx_try_fmt_vid_cap(file, priv, f);
> +	if (ret < 0)
> +		return ret;
> +
> +	csi->v_fmt = *f;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_framesizes(struct file *file, void *fh,
> +				     struct v4l2_frmsizeenum *fsize)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +	unsigned int pixels_in_word;
> +	u8 bpp;
> +
> +	fmt = find_format_by_pix(fsize->pixel_format);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	bpp = ALIGN(fmt->bpp, 8);
> +
> +	/*
> +	 * Number of pixels in one PSI-L word. The transfer happens in multiples
> +	 * of PSI-L word sizes.
> +	 */
> +	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> +
> +	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
> +	fsize->stepwise.min_width = pixels_in_word;
> +	fsize->stepwise.max_width = rounddown(MAX_WIDTH_BYTES, pixels_in_word);
> +	fsize->stepwise.step_width = pixels_in_word;
> +	fsize->stepwise.min_height = 1;
> +	fsize->stepwise.max_height = MAX_HEIGHT_BYTES;
> +	fsize->stepwise.step_height = 1;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ioctl_ops csi_ioctl_ops = {
> +	.vidioc_querycap      = ti_csi2rx_querycap,
> +	.vidioc_enum_fmt_vid_cap = ti_csi2rx_enum_fmt_vid_cap,
> +	.vidioc_try_fmt_vid_cap = ti_csi2rx_try_fmt_vid_cap,
> +	.vidioc_g_fmt_vid_cap = ti_csi2rx_g_fmt_vid_cap,
> +	.vidioc_s_fmt_vid_cap = ti_csi2rx_s_fmt_vid_cap,
> +	.vidioc_enum_framesizes = ti_csi2rx_enum_framesizes,
> +	.vidioc_reqbufs       = vb2_ioctl_reqbufs,
> +	.vidioc_create_bufs   = vb2_ioctl_create_bufs,
> +	.vidioc_prepare_buf   = vb2_ioctl_prepare_buf,
> +	.vidioc_querybuf      = vb2_ioctl_querybuf,
> +	.vidioc_qbuf          = vb2_ioctl_qbuf,
> +	.vidioc_dqbuf         = vb2_ioctl_dqbuf,
> +	.vidioc_expbuf        = vb2_ioctl_expbuf,
> +	.vidioc_streamon      = vb2_ioctl_streamon,
> +	.vidioc_streamoff     = vb2_ioctl_streamoff,
> +};
> +
> +static const struct v4l2_file_operations csi_fops = {
> +	.owner = THIS_MODULE,
> +	.open = v4l2_fh_open,
> +	.release = vb2_fop_release,
> +	.read = vb2_fop_read,
> +	.poll = vb2_fop_poll,
> +	.unlocked_ioctl = video_ioctl2,
> +	.mmap = vb2_fop_mmap,
> +};
> +
> +static int ti_csi2rx_video_register(struct ti_csi2rx_dev *csi)
> +{
> +	struct video_device *vdev = &csi->vdev;
> +	int ret, src_pad;
> +
> +	ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> +	if (ret)
> +		return ret;
> +
> +	src_pad = media_entity_get_fwnode_pad(&csi->subdev->entity,
> +					      csi->subdev->fwnode,
> +					      MEDIA_PAD_FL_SOURCE);
> +	if (src_pad < 0) {
> +		dev_err(csi->dev, "Couldn't find source pad for subdev\n");
> +		return src_pad;
> +	}
> +
> +	ret = media_create_pad_link(&csi->subdev->entity, src_pad,
> +				    &vdev->entity, 0,
> +				    MEDIA_LNK_FL_IMMUTABLE |
> +				    MEDIA_LNK_FL_ENABLED);
> +	if (ret) {
> +		video_unregister_device(vdev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int csi_async_notifier_bound(struct v4l2_async_notifier *notifier,
> +				    struct v4l2_subdev *subdev,
> +				    struct v4l2_async_subdev *asd)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +
> +	csi->subdev = subdev;
> +
> +	return 0;
> +}
> +
> +static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +	int ret;
> +
> +	ret = ti_csi2rx_video_register(csi);
> +	if (ret)
> +		return ret;
> +
> +	return v4l2_device_register_subdev_nodes(&csi->v4l2_dev);
> +}
> +
> +static const struct v4l2_async_notifier_operations csi_async_notifier_ops = {
> +	.bound = csi_async_notifier_bound,
> +	.complete = csi_async_notifier_complete,
> +};
> +
> +static int ti_csi2rx_init_subdev(struct ti_csi2rx_dev *csi)
> +{
> +	struct fwnode_handle *fwnode;
> +	struct v4l2_async_subdev *asd;
> +	struct device_node *node;
> +	int ret;
> +
> +	node = of_get_child_by_name(csi->dev->of_node, "csi-bridge");
> +	if (!node)
> +		return -EINVAL;
> +
> +	fwnode = of_fwnode_handle(node);
> +	if (!fwnode) {
> +		of_node_put(node);
> +		return -EINVAL;
> +	}
> +
> +	v4l2_async_nf_init(&csi->notifier);
> +	csi->notifier.ops = &csi_async_notifier_ops;
> +
> +	asd = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> +				       struct v4l2_async_subdev);
> +	of_node_put(node);
> +	if (IS_ERR(asd)) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return PTR_ERR(asd);
> +	}
> +
> +	ret = v4l2_async_nf_register(&csi->v4l2_dev, &csi->notifier);
> +	if (ret) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_setup_shim(struct ti_csi2rx_dev *csi)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +	unsigned int reg;
> +
> +	fmt = find_format_by_pix(csi->v_fmt.fmt.pix.pixelformat);
> +	if (!fmt) {
> +		dev_err(csi->dev, "Unknown format\n");
> +		return;
> +	}
> +
> +	/* De-assert the pixel interface reset. */
> +	reg = SHIM_CNTL_PIX_RST;
> +	writel(reg, csi->shim + SHIM_CNTL);
> +
> +	reg = SHIM_DMACNTX_EN;
> +	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_df);
> +
> +	/*
> +	 * Using the values from the documentation gives incorrect ordering for
> +	 * the luma and chroma components. In practice, the "reverse" format
> +	 * gives the correct image. So for example, if the image is in UYVY, the
> +	 * reverse would be YVYU.
> +	 */
> +	switch (fmt->fourcc) {
> +	case V4L2_PIX_FMT_UYVY:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_YVYU);
> +		break;
> +	case V4L2_PIX_FMT_VYUY:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_YUYV);
> +		break;
> +	case V4L2_PIX_FMT_YUYV:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_VYUY);
> +		break;
> +	case V4L2_PIX_FMT_YVYU:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_UYVY);
> +		break;
> +	default:
> +		/* Ignore if not YUV 4:2:2 */
> +		break;
> +	}
> +
> +	writel(reg, csi->shim + SHIM_DMACNTX);
> +
> +	reg = FIELD_PREP(SHIM_PSI_CFG0_SRC_TAG, 0) |
> +	      FIELD_PREP(SHIM_PSI_CFG0_DST_TAG, 1);
> +	writel(reg, csi->shim + SHIM_PSI_CFG0);
> +}
> +
> +static void ti_csi2rx_dma_callback(void *param)
> +{
> +	struct ti_csi2rx_buffer *buf = param;
> +	struct ti_csi2rx_dev *csi = buf->csi;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags = 0;
> +
> +	buf->vb.vb2_buf.timestamp = ktime_get_ns();
> +	buf->vb.sequence = csi->sequence++;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +
> +	WARN_ON(dma->curr != buf);
> +	vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> +
> +	/* If there are more buffers to process then start their transfer. */
> +	dma->curr = NULL;
> +	while (!list_empty(&dma->queue)) {
> +		buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +		list_del(&buf->list);
> +
> +		if (ti_csi2rx_start_dma(csi, buf)) {
> +			dev_err(csi->dev, "Failed to queue the next buffer for DMA\n");
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +		} else {
> +			dma->curr = buf;
> +			break;
> +		}
> +	}
> +
> +	if (!dma->curr)
> +		dma->state = TI_CSI2RX_DMA_IDLE;
> +
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> +			       struct ti_csi2rx_buffer *buf)
> +{
> +	unsigned long addr;
> +	struct dma_async_tx_descriptor *desc;
> +	size_t len = csi->v_fmt.fmt.pix.sizeimage;
> +	dma_cookie_t cookie;
> +	int ret = 0;
> +
> +	addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> +	desc = dmaengine_prep_slave_single(csi->dma.chan, addr, len,
> +					   DMA_DEV_TO_MEM,
> +					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc)
> +		return -EIO;
> +
> +	desc->callback = ti_csi2rx_dma_callback;
> +	desc->callback_param = buf;
> +
> +	cookie = dmaengine_submit(desc);
> +	ret = dma_submit_error(cookie);
> +	if (ret)
> +		return ret;
> +
> +	dma_async_issue_pending(csi->dma.chan);
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_queue_setup(struct vb2_queue *q, unsigned int *nbuffers,
> +				 unsigned int *nplanes, unsigned int sizes[],
> +				 struct device *alloc_devs[])
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(q);
> +	unsigned int size = csi->v_fmt.fmt.pix.sizeimage;
> +
> +	if (*nplanes) {
> +		if (sizes[0] < size)
> +			return -EINVAL;
> +		size = sizes[0];
> +	}
> +
> +	*nplanes = 1;
> +	sizes[0] = size;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_buffer_prepare(struct vb2_buffer *vb)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> +	unsigned long size = csi->v_fmt.fmt.pix.sizeimage;
> +
> +	if (vb2_plane_size(vb, 0) < size) {
> +		dev_err(csi->dev, "Data will not fit into plane\n");
> +		return -EINVAL;
> +	}
> +
> +	vb2_set_plane_payload(vb, 0, size);
> +	return 0;
> +}
> +
> +static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> +	struct ti_csi2rx_buffer *buf;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags = 0;
> +	int ret;
> +
> +	buf = container_of(vb, struct ti_csi2rx_buffer, vb.vb2_buf);
> +	buf->csi = csi;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	/*
> +	 * Usually the DMA callback takes care of queueing the pending buffers.
> +	 * But if DMA has stalled due to lack of buffers, restart it now.
> +	 */
> +	if (dma->state == TI_CSI2RX_DMA_IDLE) {
> +		ret = ti_csi2rx_start_dma(csi, buf);
> +		if (ret) {
> +			dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +			goto unlock;
> +		}
> +
> +		dma->curr = buf;
> +		dma->state = TI_CSI2RX_DMA_ACTIVE;
> +	} else {
> +		list_add_tail(&buf->list, &dma->queue);
> +	}
> +
> +unlock:
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	struct ti_csi2rx_buffer *buf, *tmp;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	if (list_empty(&dma->queue))
> +		ret = -EIO;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +	if (ret)
> +		return ret;
> +
> +	ret = media_pipeline_start(&csi->vdev.entity, &csi->pipe);
> +	if (ret)
> +		goto err;
> +
> +	ti_csi2rx_setup_shim(csi);
> +
> +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 1);
> +	if (ret)
> +		goto err_pipeline;
> +
> +	csi->sequence = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +	list_del(&buf->list);
> +	dma->state = TI_CSI2RX_DMA_ACTIVE;
> +
> +	ret = ti_csi2rx_start_dma(csi, buf);
> +	if (ret) {
> +		dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +		spin_unlock_irqrestore(&dma->lock, flags);
> +		goto err_stream;
> +	}
> +
> +	dma->curr = buf;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	return 0;
> +
> +err_stream:
> +	v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> +err_pipeline:
> +	media_pipeline_stop(&csi->vdev.entity);
> +err:
> +	spin_lock_irqsave(&dma->lock, flags);
> +	list_for_each_entry_safe(buf, tmp, &dma->queue, list) {
> +		list_del(&buf->list);
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +	}
> +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	return ret;
> +}
> +
> +static void ti_csi2rx_stop_streaming(struct vb2_queue *vq)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	struct ti_csi2rx_buffer *buf = NULL, *tmp;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags = 0;
> +	int ret;
> +
> +	media_pipeline_stop(&csi->vdev.entity);
> +
> +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop subdev stream\n");
> +
> +	writel(0, csi->shim + SHIM_CNTL);
> +
> +	ret = dmaengine_terminate_sync(csi->dma.chan);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop DMA\n");
> +
> +	writel(0, csi->shim + SHIM_DMACNTX);
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	list_for_each_entry_safe(buf, tmp, &csi->dma.queue, list) {
> +		list_del(&buf->list);
> +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +	}
> +
> +	if (dma->curr)
> +		vb2_buffer_done(&dma->curr->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +
> +	dma->curr = NULL;
> +	dma->state = TI_CSI2RX_DMA_STOPPED;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static const struct vb2_ops csi_vb2_qops = {
> +	.queue_setup = ti_csi2rx_queue_setup,
> +	.buf_prepare = ti_csi2rx_buffer_prepare,
> +	.buf_queue = ti_csi2rx_buffer_queue,
> +	.start_streaming = ti_csi2rx_start_streaming,
> +	.stop_streaming = ti_csi2rx_stop_streaming,
> +	.wait_prepare = vb2_ops_wait_prepare,
> +	.wait_finish = vb2_ops_wait_finish,
> +};
> +
> +static int ti_csi2rx_init_vb2q(struct ti_csi2rx_dev *csi)
> +{
> +	struct vb2_queue *q = &csi->vidq;
> +	int ret;
> +
> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	q->io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF | VB2_READ;
> +	q->drv_priv = csi;
> +	q->buf_struct_size = sizeof(struct ti_csi2rx_buffer);
> +	q->ops = &csi_vb2_qops;
> +	q->mem_ops = &vb2_dma_contig_memops;
> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	q->dev = dmaengine_get_dma_device(csi->dma.chan);
> +	q->lock = &csi->mutex;
> +
> +	ret = vb2_queue_init(q);
> +	if (ret)
> +		return ret;
> +
> +	csi->vdev.queue = q;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_init_dma(struct ti_csi2rx_dev *csi)
> +{
> +	struct dma_slave_config cfg;
> +	int ret;
> +
> +	INIT_LIST_HEAD(&csi->dma.queue);
> +	spin_lock_init(&csi->dma.lock);
> +
> +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> +
> +	csi->dma.chan = dma_request_chan(csi->dev, "rx0");
> +	if (IS_ERR(csi->dma.chan))
> +		return PTR_ERR(csi->dma.chan);
> +
> +	memset(&cfg, 0, sizeof(cfg));
> +
> +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_16_BYTES;

You could do this when you declare cfg, and omit the memset.

> +
> +	ret = dmaengine_slave_config(csi->dma.chan, &cfg);
> +	if (ret)

dma_release_chan() ?

> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
> +{
> +	struct media_device *mdev = &csi->mdev;
> +	struct video_device *vdev = &csi->vdev;
> +	const struct ti_csi2rx_fmt *fmt;
> +	struct v4l2_pix_format *pix_fmt = &csi->v_fmt.fmt.pix;
> +	int ret;
> +
> +	fmt = find_format_by_pix(V4L2_PIX_FMT_UYVY);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	pix_fmt->width = 640;
> +	pix_fmt->height = 480;
> +
> +	ti_csi2rx_fill_fmt(fmt, &csi->v_fmt);
> +
> +	mdev->dev = csi->dev;
> +	mdev->hw_revision = 1;
> +	strscpy(mdev->model, "TI-CSI2RX", sizeof(mdev->model));
> +	snprintf(mdev->bus_info, sizeof(mdev->bus_info), "platform:%s",
> +		 dev_name(mdev->dev));
> +
> +	media_device_init(mdev);
> +
> +	strscpy(vdev->name, TI_CSI2RX_MODULE_NAME, sizeof(vdev->name));
> +	vdev->v4l2_dev = &csi->v4l2_dev;
> +	vdev->vfl_dir = VFL_DIR_RX;
> +	vdev->fops = &csi_fops;
> +	vdev->ioctl_ops = &csi_ioctl_ops;
> +	vdev->release = video_device_release_empty;
> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_READWRITE |
> +			    V4L2_CAP_STREAMING | V4L2_CAP_IO_MC;
> +	vdev->lock = &csi->mutex;
> +	video_set_drvdata(vdev, csi);
> +
> +	csi->pad.flags = MEDIA_PAD_FL_SINK;

You'll need to provide entity ops for the vdev entity with at least
link_validate assigned. See e.g.
drivers/media/pci/intel/ipu3/ipu3-cio2-main.cdrivers/media/pci/intel/ipu3/ipu3-cio2-main.c
.

> +	ret = media_entity_pads_init(&csi->vdev.entity, 1, &csi->pad);
> +	if (ret)
> +		return ret;
> +
> +	csi->v4l2_dev.mdev = mdev;
> +
> +	ret = v4l2_device_register(csi->dev, &csi->v4l2_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = media_device_register(mdev);
> +	if (ret) {
> +		v4l2_device_unregister(&csi->v4l2_dev);
> +		media_device_cleanup(mdev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_cleanup_dma(struct ti_csi2rx_dev *csi)
> +{
> +	dma_release_channel(csi->dma.chan);
> +}
> +
> +static void ti_csi2rx_cleanup_v4l2(struct ti_csi2rx_dev *csi)
> +{
> +	media_device_unregister(&csi->mdev);
> +	v4l2_device_unregister(&csi->v4l2_dev);
> +	media_device_cleanup(&csi->mdev);
> +}
> +
> +static void ti_csi2rx_cleanup_subdev(struct ti_csi2rx_dev *csi)
> +{
> +	v4l2_async_nf_unregister(&csi->notifier);
> +	v4l2_async_nf_cleanup(&csi->notifier);
> +}
> +
> +static void ti_csi2rx_cleanup_vb2q(struct ti_csi2rx_dev *csi)
> +{
> +	vb2_queue_release(&csi->vidq);
> +}
> +
> +static int ti_csi2rx_probe(struct platform_device *pdev)
> +{
> +	struct ti_csi2rx_dev *csi;
> +	struct resource *res;
> +	int ret;
> +
> +	csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);
> +	if (!csi)
> +		return -ENOMEM;
> +
> +	csi->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, csi);
> +
> +	mutex_init(&csi->mutex);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	csi->shim = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(csi->shim))

Remember mutex_destroy(). I'd add one more label below.

> +		return PTR_ERR(csi->shim);
> +
> +	ret = ti_csi2rx_init_dma(csi);
> +	if (ret)
> +		return ret;
> +
> +	ret = ti_csi2rx_v4l2_init(csi);
> +	if (ret)
> +		goto err_dma;
> +
> +	ret = ti_csi2rx_init_vb2q(csi);
> +	if (ret)
> +		goto err_v4l2;
> +
> +	ret = ti_csi2rx_init_subdev(csi);
> +	if (ret)
> +		goto err_vb2q;
> +
> +	ret = of_platform_populate(csi->dev->of_node, NULL, NULL, csi->dev);
> +	if (ret) {
> +		dev_err(csi->dev, "Failed to create children: %d\n", ret);
> +		goto err_subdev;
> +	}
> +
> +	return 0;
> +
> +err_subdev:
> +	ti_csi2rx_cleanup_subdev(csi);
> +err_vb2q:
> +	ti_csi2rx_cleanup_vb2q(csi);
> +err_v4l2:
> +	ti_csi2rx_cleanup_v4l2(csi);
> +err_dma:
> +	ti_csi2rx_cleanup_dma(csi);
> +	return ret;
> +}
> +
> +static int ti_csi2rx_remove(struct platform_device *pdev)
> +{
> +	struct ti_csi2rx_dev *csi = platform_get_drvdata(pdev);
> +
> +	if (vb2_is_busy(&csi->vidq))
> +		return -EBUSY;

Hmm. I don't think this is useful.

Unbinding MC-enabled devices is broken at the moment, so I think you can
safely ignore this bit in drivers.

> +
> +	video_unregister_device(&csi->vdev);
> +
> +	ti_csi2rx_cleanup_vb2q(csi);
> +	ti_csi2rx_cleanup_subdev(csi);
> +	ti_csi2rx_cleanup_v4l2(csi);
> +	ti_csi2rx_cleanup_dma(csi);

mutex_destroy() here, too.

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ti_csi2rx_of_match[] = {
> +	{ .compatible = "ti,j721e-csi2rx", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ti_csi2rx_of_match);
> +
> +static struct platform_driver ti_csi2rx_pdrv = {
> +	.probe = ti_csi2rx_probe,
> +	.remove = ti_csi2rx_remove,
> +	.driver = {
> +		.name = TI_CSI2RX_MODULE_NAME,
> +		.of_match_table = ti_csi2rx_of_match,
> +	},
> +};
> +
> +module_platform_driver(ti_csi2rx_pdrv);
> +
> +MODULE_DESCRIPTION("TI J721E CSI2 RX Driver");
> +MODULE_AUTHOR("Pratyush Yadav <p.yadav@ti.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION("1.0");

Hi Laurent,

Thanks for your review and sorry for the late reply.

On 23/01/22 08:25PM, Laurent Pinchart wrote:
> Hi Pratyush,
> 
> Thank you for the patch.
> 
> On Fri, Jan 21, 2022 at 07:59:01PM +0530, Pratyush Yadav wrote:
> > TI's J721E uses the Cadence CSI2RX and DPHY peripherals to facilitate
> > capture over a CSI-2 bus.
> > 
> > The Cadence CSI2RX IP acts as a bridge between the TI specific parts and
> > the CSI-2 protocol parts. TI then has a wrapper on top of this bridge
> > called the SHIM layer. It takes in data from stream 0, repacks it, and
> > sends it to memory over PSI-L DMA.
> > 
> > This driver acts as the "front end" to V4L2 client applications. It
> > implements the required ioctls and buffer operations, passes the
> > necessary calls on to the bridge, programs the SHIM layer, and performs
> > DMA via the dmaengine API to finally return the data to a buffer
> > supplied by the application.
> > 
> > Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> > 
> > ---
> > 
> > (no changes since v5)
> > 
> > Changes in v5:
> > - Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
> >   since the Rx mode DPHY now has a separate driver.
> > - Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be done
> >   at media_pipeline_start().
> > - Do not assign flags.
> > - Fix error handling in ti_csi2rx_start_streaming(). Free up vb2 buffers
> >   when media_pipeline_start() fails.
> > 
> > Changes in v4:
> > - Acquire the media device's graph_mutex before starting the graph walk.
> > - Call media_graph_walk_init() and media_graph_walk_cleanup() when
> >   starting and ending the graph walk respectively.
> > - Reduce max frame height and width in enum_framesizes. Currently they
> >   are set to UINT_MAX but they must be a multiple of step_width, so they
> >   need to be rounded down. Also, these values are absurdly large which
> >   causes some userspace applications like gstreamer to trip up. While it
> >   is not generally right to change the kernel for an application bug, it
> >   is not such a big deal here. This change is replacing one set of
> >   absurdly large arbitrary values with another set of smaller but still
> >   absurdly large arbitrary values. Both limits are unlikely to be hit in
> >   practice.
> > 
> > Changes in v3:
> > - Move DMA related fields in struct ti_csi2rx_dma.
> > - Protect DMA buffer queue with a spinlock to make sure the queue buffer
> >   and DMA callback don't race on it.
> > - Track the current DMA state. It might go idle because of a lack of
> >   buffers. This state can be used to restart it if needed.
> > - Do not include the current buffer in the pending queue. It is slightly
> >   better modelling than leaving it at the head of the pending queue.
> > - Use the buffer as the callback argument, and add a reference to csi in it.
> > - If queueing a buffer to DMA fails, the buffer gets leaked and DMA gets
> >   stalled with. Instead, report the error to vb2 and queue the next
> >   buffer in the pending queue.
> > - DMA gets stalled if we run out of buffers since the callback is the
> >   only one that fires subsequent transfers and it is no longer being
> >   called. Check for that when queueing buffers and restart DMA if
> >   needed.
> > - Do not put of node until we are done using the fwnode.
> > - Set inital format to UYVY 640x480.
> > 
> > Changes in v2:
> > - Use dmaengine_get_dma_device() instead of directly accessing
> >   dma->device->dev.
> > - Do not set dst_addr_width when configuring slave DMA.
> > - Move to a separate subdir and rename to j721e-csi2rx.c
> > - Convert compatible to ti,j721e-csi2rx.
> > - Move to use Media Controller centric APIs.
> > - Improve cleanup in probe when one of the steps fails.
> > - Add colorspace to formats database.
> > - Set hw_revision on media_device.
> > - Move video device initialization to probe time instead of register time.
> > 
> >  MAINTAINERS                                   |   6 +
> >  drivers/media/platform/Kconfig                |  12 +
> >  drivers/media/platform/ti/Makefile            |   1 +
> >  .../media/platform/ti/j721e-csi2rx/Makefile   |   2 +
> >  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 913 ++++++++++++++++++
> >  5 files changed, 934 insertions(+)
> >  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
> >  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 3b8fa4e5047f..2a8ebf17462e 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -19181,6 +19181,12 @@ S:	Odd Fixes
> >  F:	drivers/clk/ti/
> >  F:	include/linux/clk/ti.h
> >  
> > +TI J721E CSI2RX DRIVER
> > +M:	Pratyush Yadav <p.yadav@ti.com>
> > +L:	linux-media@vger.kernel.org
> > +S:	Supported
> > +F:	drivers/media/platform/ti/j721e-csi2rx/
> > +
> >  TI DAVINCI MACHINE SUPPORT
> >  M:	Sekhar Nori <nsekhar@ti.com>
> >  R:	Bartosz Golaszewski <brgl@bgdev.pl>
> > diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> > index 9fbdba0fd1e7..0fa58563d93b 100644
> > --- a/drivers/media/platform/Kconfig
> > +++ b/drivers/media/platform/Kconfig
> > @@ -216,6 +216,18 @@ config VIDEO_RCAR_ISP
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called rcar-isp.
> >  
> > +config VIDEO_TI_J721E_CSI2RX
> > +	tristate "TI J721E CSI2RX wrapper layer driver"
> > +	depends on VIDEO_DEV && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
> > +	depends on MEDIA_SUPPORT && MEDIA_CONTROLLER
> > +	depends on PHY_CADENCE_DPHY_RX && VIDEO_CADENCE_CSI2RX
> > +	depends on ARCH_K3 || COMPILE_TEST
> > +	select VIDEOBUF2_DMA_CONTIG
> > +	select V4L2_FWNODE
> > +	help
> > +	  Support for TI CSI2RX wrapper layer. This just enables the wrapper driver.
> > +	  The Cadence CSI2RX bridge driver needs to be enabled separately.
> > +
> >  endif # V4L_PLATFORM_DRIVERS
> >  
> >  menuconfig V4L_MEM2MEM_DRIVERS
> > diff --git a/drivers/media/platform/ti/Makefile b/drivers/media/platform/ti/Makefile
> > index bbc737ccbbea..17c9cfb74f66 100644
> > --- a/drivers/media/platform/ti/Makefile
> > +++ b/drivers/media/platform/ti/Makefile
> > @@ -1,3 +1,4 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >  obj-y += cal/
> >  obj-y += vpe/
> > +obj-y += j721e-csi2rx/
> 
> Alphabetical order maybe ?
> 
> > diff --git a/drivers/media/platform/ti/j721e-csi2rx/Makefile b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> > new file mode 100644
> > index 000000000000..377afc1d6280
> > --- /dev/null
> > +++ b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> > @@ -0,0 +1,2 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +obj-$(CONFIG_VIDEO_TI_J721E_CSI2RX) += j721e-csi2rx.o
> > diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> > new file mode 100644
> > index 000000000000..43f31f161f43
> > --- /dev/null
> > +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> > @@ -0,0 +1,913 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * TI CSI2 RX driver.
> > + *
> > + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
> > + *
> > + * Author: Pratyush Yadav <p.yadav@ti.com>
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/dmaengine.h>
> > +#include <linux/of_platform.h>
> 
> Alphabetical order would be nice here too.
> 
> > +
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-ioctl.h>
> > +#include <media/videobuf2-dma-contig.h>
> > +
> > +#define TI_CSI2RX_MODULE_NAME		"j721e-csi2rx"
> > +
> > +#define SHIM_CNTL			0x10
> > +#define SHIM_CNTL_PIX_RST		BIT(0)
> > +
> > +#define SHIM_DMACNTX			0x20
> > +#define SHIM_DMACNTX_EN			BIT(31)
> > +#define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
> > +#define SHIM_DMACNTX_FMT		GENMASK(5, 0)
> > +#define SHIM_DMACNTX_UYVY		0
> > +#define SHIM_DMACNTX_VYUY		1
> > +#define SHIM_DMACNTX_YUYV		2
> > +#define SHIM_DMACNTX_YVYU		3
> > +
> > +#define SHIM_PSI_CFG0			0x24
> > +#define SHIM_PSI_CFG0_SRC_TAG		GENMASK(15, 0)
> > +#define SHIM_PSI_CFG0_DST_TAG		GENMASK(31, 15)
> > +
> > +#define CSI_DF_YUV420			0x18
> > +#define CSI_DF_YUV422			0x1e
> > +#define CSI_DF_RGB444			0x20
> > +#define CSI_DF_RGB888			0x24
> 
> https://lore.kernel.org/linux-media/20220123160857.24161-2-laurent.pinchart+renesas@ideasonboard.com/
> 
> :-)
> 
> > +
> > +#define PSIL_WORD_SIZE_BYTES		16
> > +/*
> > + * There are no hard limits on the width or height. The DMA engine can handle
> > + * all sizes. The max width and height are arbitrary numbers for this driver.
> > + * Use 16M * 16M as the arbitrary limit. It is large enough that it is unlikely
> > + * the limit will be hit in practice.
> > + */
> > +#define MAX_WIDTH_BYTES			SZ_16M
> > +#define MAX_HEIGHT_BYTES		SZ_16M
> > +
> > +struct ti_csi2rx_fmt {
> > +	u32				fourcc;	/* Four character code. */
> > +	u32				code;	/* Mbus code. */
> > +	enum v4l2_colorspace		colorspace;
> > +	u32				csi_df;	/* CSI Data format. */
> 
> It's called data type in CSI-2, not data format.
> 
> > +	u8				bpp;	/* Bits per pixel. */
> > +};
> > +
> > +struct ti_csi2rx_buffer {
> > +	/* Common v4l2 buffer. Must be first. */
> > +	struct vb2_v4l2_buffer		vb;
> > +	struct list_head		list;
> > +	struct ti_csi2rx_dev		*csi;
> > +};
> > +
> > +enum ti_csi2rx_dma_state {
> > +	TI_CSI2RX_DMA_STOPPED,	/* Streaming not started yet. */
> > +	TI_CSI2RX_DMA_IDLE,	/* Streaming but no pending DMA operation. */
> > +	TI_CSI2RX_DMA_ACTIVE,	/* Streaming and pending DMA operation. */
> > +};
> > +
> > +struct ti_csi2rx_dma {
> > +	/* Protects all fields in this struct. */
> > +	spinlock_t			lock;
> > +	struct dma_chan			*chan;
> > +	/* Buffers queued to the driver, waiting to be processed by DMA. */
> > +	struct list_head		queue;
> > +	enum ti_csi2rx_dma_state	state;
> > +	/*
> > +	 * Current buffer being processed by DMA. NULL if no buffer is being
> > +	 * processed.
> > +	 */
> > +	struct ti_csi2rx_buffer		*curr;
> > +};
> > +
> > +struct ti_csi2rx_dev {
> > +	struct device			*dev;
> > +	void __iomem			*shim;
> > +	struct v4l2_device		v4l2_dev;
> > +	struct video_device		vdev;
> > +	struct media_device		mdev;
> > +	struct media_pipeline		pipe;
> > +	struct media_pad		pad;
> > +	struct v4l2_async_notifier	notifier;
> > +	struct v4l2_subdev		*subdev;
> > +	struct vb2_queue		vidq;
> > +	struct mutex			mutex; /* To serialize ioctls. */
> > +	struct v4l2_format		v_fmt;
> > +	struct ti_csi2rx_dma		dma;
> > +	u32				sequence;
> > +};
> > +
> > +static const struct ti_csi2rx_fmt formats[] = {
> > +	{
> > +		.fourcc			= V4L2_PIX_FMT_YUYV,
> > +		.code			= MEDIA_BUS_FMT_YUYV8_2X8,
> > +		.colorspace		= V4L2_COLORSPACE_SRGB,
> > +		.csi_df			= CSI_DF_YUV422,
> > +		.bpp			= 16,
> > +	}, {
> > +		.fourcc			= V4L2_PIX_FMT_UYVY,
> > +		.code			= MEDIA_BUS_FMT_UYVY8_2X8,
> > +		.colorspace		= V4L2_COLORSPACE_SRGB,
> > +		.csi_df			= CSI_DF_YUV422,
> > +		.bpp			= 16,
> > +	}, {
> > +		.fourcc			= V4L2_PIX_FMT_YVYU,
> > +		.code			= MEDIA_BUS_FMT_YVYU8_2X8,
> > +		.colorspace		= V4L2_COLORSPACE_SRGB,
> > +		.csi_df			= CSI_DF_YUV422,
> > +		.bpp			= 16,
> > +	}, {
> > +		.fourcc			= V4L2_PIX_FMT_VYUY,
> > +		.code			= MEDIA_BUS_FMT_VYUY8_2X8,
> > +		.colorspace		= V4L2_COLORSPACE_SRGB,
> > +		.csi_df			= CSI_DF_YUV422,
> > +		.bpp			= 16,
> > +	},
> > +
> > +	/* More formats can be supported but they are not listed for now. */
> > +};
> > +
> > +static const unsigned int num_formats = ARRAY_SIZE(formats);
> > +
> > +/* Forward declaration needed by ti_csi2rx_dma_callback. */
> > +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> > +			       struct ti_csi2rx_buffer *buf);
> > +
> > +static const struct ti_csi2rx_fmt *find_format_by_pix(u32 pixelformat)
> > +{
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < num_formats; i++) {
> > +		if (formats[i].fourcc == pixelformat)
> > +			return &formats[i];
> > +	}
> > +
> > +	return NULL;
> > +}
> > +
> > +static void ti_csi2rx_fill_fmt(const struct ti_csi2rx_fmt *csi_fmt,
> > +			       struct v4l2_format *v4l2_fmt)
> > +{
> > +	struct v4l2_pix_format *pix = &v4l2_fmt->fmt.pix;
> > +	u32 bpl;
> > +
> > +	v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > +	pix->pixelformat = csi_fmt->fourcc;
> > +	pix->colorspace = csi_fmt->colorspace;
> 
> I'd drop this (and the colorspace field in ti_csi2rx_fmt). This driver
> doesn't care about colorspaces, it should accept any value set by
> userspace, which should match the colorspace produced by the source
> subdev.
> 
> ti_csi2rx_v4l2_init() will have to set a default colorspace explicitly.
> 
> > +	pix->sizeimage = pix->height * pix->width * (csi_fmt->bpp / 8);
> > +
> > +	bpl = (pix->width * ALIGN(csi_fmt->bpp, 8)) >> 3;
> > +	pix->bytesperline = ALIGN(bpl, 16);
> > +}
> > +
> > +static int ti_csi2rx_querycap(struct file *file, void *priv,
> > +			      struct v4l2_capability *cap)
> > +{
> > +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> > +
> > +	strscpy(cap->driver, TI_CSI2RX_MODULE_NAME, sizeof(cap->driver));
> > +	strscpy(cap->card, TI_CSI2RX_MODULE_NAME, sizeof(cap->card));
> > +
> > +	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
> > +		 dev_name(csi->dev));
> 
> Depending on which series gets merged, you can drop this line:
> 
> https://lore.kernel.org/linux-media/20220122163656.168440-1-sakari.ailus@linux.intel.com/

I don't see it merged yet, so leaving this as-is.

> 
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_enum_fmt_vid_cap(struct file *file, void *priv,
> > +				      struct v4l2_fmtdesc *f)
> > +{
> > +	if (f->index >= num_formats)
> > +		return -EINVAL;
> > +
> > +	memset(f->reserved, 0, sizeof(f->reserved));
> > +	f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > +	f->pixelformat = formats[f->index].fourcc;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_g_fmt_vid_cap(struct file *file, void *prov,
> > +				   struct v4l2_format *f)
> > +{
> > +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> > +
> > +	*f = csi->v_fmt;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_try_fmt_vid_cap(struct file *file, void *priv,
> > +				     struct v4l2_format *f)
> > +{
> > +	const struct ti_csi2rx_fmt *fmt;
> > +
> > +	/*
> > +	 * Default to the first format if the requested pixel format code isn't
> > +	 * supported.
> > +	 */
> > +	fmt = find_format_by_pix(f->fmt.pix.pixelformat);
> > +	if (!fmt)
> > +		fmt = &formats[0];
> > +
> > +	if (f->fmt.pix.field == V4L2_FIELD_ANY)
> > +		f->fmt.pix.field = V4L2_FIELD_NONE;
> > +
> > +	if (f->fmt.pix.field != V4L2_FIELD_NONE)
> > +		return -EINVAL;
> 
> You should adjust the field, not return an error, so this can just
> become
> 
> 	/* Interlaced formats are not supported. */
> 	f->fmt.pix.field = V4L2_FIELD_NONE;
> 
> > +
> > +	ti_csi2rx_fill_fmt(fmt, f);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_s_fmt_vid_cap(struct file *file, void *priv,
> > +				   struct v4l2_format *f)
> > +{
> > +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> > +	struct vb2_queue *q = &csi->vidq;
> > +	int ret;
> > +
> > +	if (vb2_is_busy(q))
> > +		return -EBUSY;
> > +
> > +	ret = ti_csi2rx_try_fmt_vid_cap(file, priv, f);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	csi->v_fmt = *f;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_enum_framesizes(struct file *file, void *fh,
> > +				     struct v4l2_frmsizeenum *fsize)
> > +{
> > +	const struct ti_csi2rx_fmt *fmt;
> > +	unsigned int pixels_in_word;
> > +	u8 bpp;
> > +
> > +	fmt = find_format_by_pix(fsize->pixel_format);
> > +	if (!fmt)
> > +		return -EINVAL;
> > +
> > +	bpp = ALIGN(fmt->bpp, 8);
> > +
> > +	/*
> > +	 * Number of pixels in one PSI-L word. The transfer happens in multiples
> > +	 * of PSI-L word sizes.
> > +	 */
> > +	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> > +
> > +	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
> > +	fsize->stepwise.min_width = pixels_in_word;
> > +	fsize->stepwise.max_width = rounddown(MAX_WIDTH_BYTES, pixels_in_word);
> > +	fsize->stepwise.step_width = pixels_in_word;
> > +	fsize->stepwise.min_height = 1;
> > +	fsize->stepwise.max_height = MAX_HEIGHT_BYTES;
> > +	fsize->stepwise.step_height = 1;
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct v4l2_ioctl_ops csi_ioctl_ops = {
> > +	.vidioc_querycap      = ti_csi2rx_querycap,
> > +	.vidioc_enum_fmt_vid_cap = ti_csi2rx_enum_fmt_vid_cap,
> > +	.vidioc_try_fmt_vid_cap = ti_csi2rx_try_fmt_vid_cap,
> > +	.vidioc_g_fmt_vid_cap = ti_csi2rx_g_fmt_vid_cap,
> > +	.vidioc_s_fmt_vid_cap = ti_csi2rx_s_fmt_vid_cap,
> > +	.vidioc_enum_framesizes = ti_csi2rx_enum_framesizes,
> > +	.vidioc_reqbufs       = vb2_ioctl_reqbufs,
> > +	.vidioc_create_bufs   = vb2_ioctl_create_bufs,
> > +	.vidioc_prepare_buf   = vb2_ioctl_prepare_buf,
> > +	.vidioc_querybuf      = vb2_ioctl_querybuf,
> > +	.vidioc_qbuf          = vb2_ioctl_qbuf,
> > +	.vidioc_dqbuf         = vb2_ioctl_dqbuf,
> > +	.vidioc_expbuf        = vb2_ioctl_expbuf,
> > +	.vidioc_streamon      = vb2_ioctl_streamon,
> > +	.vidioc_streamoff     = vb2_ioctl_streamoff,
> > +};
> > +
> > +static const struct v4l2_file_operations csi_fops = {
> > +	.owner = THIS_MODULE,
> > +	.open = v4l2_fh_open,
> > +	.release = vb2_fop_release,
> > +	.read = vb2_fop_read,
> > +	.poll = vb2_fop_poll,
> > +	.unlocked_ioctl = video_ioctl2,
> > +	.mmap = vb2_fop_mmap,
> > +};
> > +
> > +static int ti_csi2rx_video_register(struct ti_csi2rx_dev *csi)
> > +{
> > +	struct video_device *vdev = &csi->vdev;
> > +	int ret, src_pad;
> > +
> > +	ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> > +	if (ret)
> > +		return ret;
> > +
> > +	src_pad = media_entity_get_fwnode_pad(&csi->subdev->entity,
> > +					      csi->subdev->fwnode,
> > +					      MEDIA_PAD_FL_SOURCE);
> > +	if (src_pad < 0) {
> > +		dev_err(csi->dev, "Couldn't find source pad for subdev\n");
> > +		return src_pad;
> > +	}
> > +
> > +	ret = media_create_pad_link(&csi->subdev->entity, src_pad,
> > +				    &vdev->entity, 0,
> > +				    MEDIA_LNK_FL_IMMUTABLE |
> > +				    MEDIA_LNK_FL_ENABLED);
> > +	if (ret) {
> > +		video_unregister_device(vdev);
> > +		return ret;
> > +	}
> 
> This can be simplified by using v4l2_create_fwnode_links_to_pad().

I don't think it can. v4l2_create_fwnode_links_to_pad() expects the sink 
pad to be backed by a v4l2 subdev. But in this case, the sink pad is 
backed by a video device instead.

> 
> > +
> > +	return 0;
> > +}
> > +
> > +static int csi_async_notifier_bound(struct v4l2_async_notifier *notifier,
> > +				    struct v4l2_subdev *subdev,
> > +				    struct v4l2_async_subdev *asd)
> > +{
> > +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> > +
> > +	csi->subdev = subdev;
> > +
> > +	return 0;
> > +}
> > +
> > +static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
> > +{
> > +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> > +	int ret;
> > +
> > +	ret = ti_csi2rx_video_register(csi);
> 
> I would inline the ti_csi2rx_video_register() function here, it's not
> large, and it's only called in a single place.

I'd guess the compiler would do it anyway but ok.

> 
> > +	if (ret)
> > +		return ret;
> > +
> > +	return v4l2_device_register_subdev_nodes(&csi->v4l2_dev);
> > +}
> > +
> > +static const struct v4l2_async_notifier_operations csi_async_notifier_ops = {
> > +	.bound = csi_async_notifier_bound,
> > +	.complete = csi_async_notifier_complete,
> > +};
> > +
> > +static int ti_csi2rx_init_subdev(struct ti_csi2rx_dev *csi)
> > +{
> > +	struct fwnode_handle *fwnode;
> > +	struct v4l2_async_subdev *asd;
> > +	struct device_node *node;
> > +	int ret;
> > +
> > +	node = of_get_child_by_name(csi->dev->of_node, "csi-bridge");
> > +	if (!node)
> > +		return -EINVAL;
> > +
> > +	fwnode = of_fwnode_handle(node);
> > +	if (!fwnode) {
> > +		of_node_put(node);
> > +		return -EINVAL;
> > +	}
> > +
> > +	v4l2_async_nf_init(&csi->notifier);
> > +	csi->notifier.ops = &csi_async_notifier_ops;
> > +
> > +	asd = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> > +				       struct v4l2_async_subdev);
> > +	of_node_put(node);
> > +	if (IS_ERR(asd)) {
> > +		v4l2_async_nf_cleanup(&csi->notifier);
> > +		return PTR_ERR(asd);
> > +	}
> > +
> > +	ret = v4l2_async_nf_register(&csi->v4l2_dev, &csi->notifier);
> > +	if (ret) {
> > +		v4l2_async_nf_cleanup(&csi->notifier);
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void ti_csi2rx_setup_shim(struct ti_csi2rx_dev *csi)
> > +{
> > +	const struct ti_csi2rx_fmt *fmt;
> > +	unsigned int reg;
> > +
> > +	fmt = find_format_by_pix(csi->v_fmt.fmt.pix.pixelformat);
> > +	if (!fmt) {
> > +		dev_err(csi->dev, "Unknown format\n");
> > +		return;
> > +	}
> > +
> > +	/* De-assert the pixel interface reset. */
> > +	reg = SHIM_CNTL_PIX_RST;
> > +	writel(reg, csi->shim + SHIM_CNTL);
> > +
> > +	reg = SHIM_DMACNTX_EN;
> > +	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_df);
> > +
> > +	/*
> > +	 * Using the values from the documentation gives incorrect ordering for
> > +	 * the luma and chroma components. In practice, the "reverse" format
> > +	 * gives the correct image. So for example, if the image is in UYVY, the
> > +	 * reverse would be YVYU.
> 
> Are you sure this is an issue in the documentation, not in the
> implementation of the source subdev ?

I have not probed the data lines or anything, but I see that on AM65x 
the same camera module and driver produce the output in the correct 
order. So I would guess that the source subdev is not the problem here. 
I do not have any other YUV cameras to double-check this with though.

> 
> > +	 */
> > +	switch (fmt->fourcc) {
> > +	case V4L2_PIX_FMT_UYVY:
> > +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > +					SHIM_DMACNTX_YVYU);
> > +		break;
> > +	case V4L2_PIX_FMT_VYUY:
> > +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > +					SHIM_DMACNTX_YUYV);
> > +		break;
> > +	case V4L2_PIX_FMT_YUYV:
> > +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > +					SHIM_DMACNTX_VYUY);
> > +		break;
> > +	case V4L2_PIX_FMT_YVYU:
> > +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> > +					SHIM_DMACNTX_UYVY);
> > +		break;
> > +	default:
> > +		/* Ignore if not YUV 4:2:2 */
> > +		break;
> > +	}
> > +
> > +	writel(reg, csi->shim + SHIM_DMACNTX);
> > +
> > +	reg = FIELD_PREP(SHIM_PSI_CFG0_SRC_TAG, 0) |
> > +	      FIELD_PREP(SHIM_PSI_CFG0_DST_TAG, 1);
> > +	writel(reg, csi->shim + SHIM_PSI_CFG0);
> > +}
> > +
> > +static void ti_csi2rx_dma_callback(void *param)
> > +{
> > +	struct ti_csi2rx_buffer *buf = param;
> > +	struct ti_csi2rx_dev *csi = buf->csi;
> > +	struct ti_csi2rx_dma *dma = &csi->dma;
> > +	unsigned long flags = 0;
> 
> No need to initialize flags to 0.
> 
> > +
> > +	buf->vb.vb2_buf.timestamp = ktime_get_ns();
> > +	buf->vb.sequence = csi->sequence++;
> 
> Is there any hardware frame counter that could be used, to detect
> dropped frames ? Or maybe a SOF hardware interrupt somewhere (either in
> the SHIM or the CSI-2 receiver) ?

There is a register in the Cadence CSI2RX core (driven by 
drivers/media/platform/cadence/cdns-csi2rx.c) that tells the frame 
number. But I don't see any easy way to get that information into this 
driver.

> 
> > +
> > +	spin_lock_irqsave(&dma->lock, flags);
> > +
> > +	WARN_ON(dma->curr != buf);
> > +	vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> > +
> > +	/* If there are more buffers to process then start their transfer. */
> > +	dma->curr = NULL;
> > +	while (!list_empty(&dma->queue)) {
> > +		buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> > +		list_del(&buf->list);
> > +
> > +		if (ti_csi2rx_start_dma(csi, buf)) {
> > +			dev_err(csi->dev, "Failed to queue the next buffer for DMA\n");
> > +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> 
> If this buffer fails to be queued, do you expect that the next buffer in
> the list would succeed ? It seems to be a fatal error to me.

Not always. For example, ti_csi2rx_start_dma() calls 
dmaengine_prep_slave_single(). This would go to udma_prep_slave_sg(). 
This function makes some malloc() calls for example. Under memory 
pressure, those calls might fail. But on subsequent runs they might 
succeed if more memory is available.

I admit this is very unlikely to happen in practice. I don't know the 
UDMA driver well enough to comment on whether or not it can fail due to 
some resource constraints under stress. But I don't think it is this 
driver's place to decide what DMA error is recoverable and which is not.

> 
> > +		} else {
> > +			dma->curr = buf;
> > +			break;
> 
> Shouldn't all pending buffers be queued to the DMA engine ? It seems
> that you're queuing one buffer at a time, which would cause an underrun
> if the system is too slow to queue the next buffer during vertical
> blanking. It defeats the point of having multiple buffers in the V4L2
> queue. You should instead queue the buffers to the DMA engine as soon as
> they're received by the driver.

Okay, I can do that in this driver. But one point to note here is that 
the UDMA driver does not currently support pushing multiple buffers for 
processing at the same time. It pushes one buffer and once it gets an 
interrupt for its completion, it pushes the next one.

Queuing multiple buffers from CSI driver side would still be a bit 
faster since the next buffer would be pushed to the hardware ring in the 
interrupt handler, instead of having to wait for the callback to 
execute. But at the end of the day we would not end up pushing multiple 
buffers to the _hardware_.

That of course is a limitation of the TI UDMA driver that needs to be 
fixed, but I can at least queue all the buffer from the CSI driver side.

> 
> > +		}
> > +	}
> > +
> > +	if (!dma->curr)
> > +		dma->state = TI_CSI2RX_DMA_IDLE;
> > +
> > +	spin_unlock_irqrestore(&dma->lock, flags);
> > +}
> > +
> > +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> > +			       struct ti_csi2rx_buffer *buf)
> > +{
> > +	unsigned long addr;
> > +	struct dma_async_tx_descriptor *desc;
> > +	size_t len = csi->v_fmt.fmt.pix.sizeimage;
> > +	dma_cookie_t cookie;
> > +	int ret = 0;
> > +
> > +	addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> > +	desc = dmaengine_prep_slave_single(csi->dma.chan, addr, len,
> > +					   DMA_DEV_TO_MEM,
> > +					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> > +	if (!desc)
> > +		return -EIO;
> > +
> > +	desc->callback = ti_csi2rx_dma_callback;
> > +	desc->callback_param = buf;
> > +
> > +	cookie = dmaengine_submit(desc);
> > +	ret = dma_submit_error(cookie);
> > +	if (ret)
> > +		return ret;
> > +
> > +	dma_async_issue_pending(csi->dma.chan);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_queue_setup(struct vb2_queue *q, unsigned int *nbuffers,
> > +				 unsigned int *nplanes, unsigned int sizes[],
> > +				 struct device *alloc_devs[])
> > +{
> > +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(q);
> > +	unsigned int size = csi->v_fmt.fmt.pix.sizeimage;
> > +
> > +	if (*nplanes) {
> > +		if (sizes[0] < size)
> > +			return -EINVAL;
> > +		size = sizes[0];
> > +	}
> > +
> > +	*nplanes = 1;
> > +	sizes[0] = size;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_buffer_prepare(struct vb2_buffer *vb)
> > +{
> > +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> > +	unsigned long size = csi->v_fmt.fmt.pix.sizeimage;
> > +
> > +	if (vb2_plane_size(vb, 0) < size) {
> > +		dev_err(csi->dev, "Data will not fit into plane\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	vb2_set_plane_payload(vb, 0, size);
> > +	return 0;
> > +}
> > +
> > +static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
> > +{
> > +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> > +	struct ti_csi2rx_buffer *buf;
> > +	struct ti_csi2rx_dma *dma = &csi->dma;
> > +	unsigned long flags = 0;
> > +	int ret;
> > +
> > +	buf = container_of(vb, struct ti_csi2rx_buffer, vb.vb2_buf);
> > +	buf->csi = csi;
> > +
> > +	spin_lock_irqsave(&dma->lock, flags);
> > +	/*
> > +	 * Usually the DMA callback takes care of queueing the pending buffers.
> > +	 * But if DMA has stalled due to lack of buffers, restart it now.
> > +	 */
> > +	if (dma->state == TI_CSI2RX_DMA_IDLE) {
> > +		ret = ti_csi2rx_start_dma(csi, buf);
> > +		if (ret) {
> > +			dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> > +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> > +			goto unlock;
> > +		}
> > +
> > +		dma->curr = buf;
> > +		dma->state = TI_CSI2RX_DMA_ACTIVE;
> > +	} else {
> > +		list_add_tail(&buf->list, &dma->queue);
> > +	}
> > +
> > +unlock:
> > +	spin_unlock_irqrestore(&dma->lock, flags);
> > +}
> > +
> > +static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
> > +{
> > +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> > +	struct ti_csi2rx_dma *dma = &csi->dma;
> > +	struct ti_csi2rx_buffer *buf, *tmp;
> > +	unsigned long flags;
> > +	int ret = 0;
> > +
> > +	spin_lock_irqsave(&dma->lock, flags);
> > +	if (list_empty(&dma->queue))
> > +		ret = -EIO;
> > +	spin_unlock_irqrestore(&dma->lock, flags);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = media_pipeline_start(&csi->vdev.entity, &csi->pipe);
> > +	if (ret)
> > +		goto err;
> > +
> > +	ti_csi2rx_setup_shim(csi);
> > +
> > +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 1);
> > +	if (ret)
> > +		goto err_pipeline;
> > +
> > +	csi->sequence = 0;
> > +
> > +	spin_lock_irqsave(&dma->lock, flags);
> > +	buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> > +	list_del(&buf->list);
> > +	dma->state = TI_CSI2RX_DMA_ACTIVE;
> > +
> > +	ret = ti_csi2rx_start_dma(csi, buf);
> 
> Shouldn't you start DMA before starting the source subdev ? You may miss
> the first frame otherwise.

Okay, I will do that.

> 
> > +	if (ret) {
> > +		dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> > +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> > +		spin_unlock_irqrestore(&dma->lock, flags);
> > +		goto err_stream;
> > +	}
> > +
> > +	dma->curr = buf;
> > +	spin_unlock_irqrestore(&dma->lock, flags);
> > +
> > +	return 0;
> > +
> > +err_stream:
> > +	v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> > +err_pipeline:
> > +	media_pipeline_stop(&csi->vdev.entity);
> > +err:
> > +	spin_lock_irqsave(&dma->lock, flags);
> > +	list_for_each_entry_safe(buf, tmp, &dma->queue, list) {
> > +		list_del(&buf->list);
> > +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> > +	}
> > +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> > +	spin_unlock_irqrestore(&dma->lock, flags);
> > +
> > +	return ret;
> > +}
> > +
> > +static void ti_csi2rx_stop_streaming(struct vb2_queue *vq)
> > +{
> > +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> > +	struct ti_csi2rx_buffer *buf = NULL, *tmp;
> > +	struct ti_csi2rx_dma *dma = &csi->dma;
> > +	unsigned long flags = 0;
> > +	int ret;
> > +
> > +	media_pipeline_stop(&csi->vdev.entity);
> > +
> > +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> > +	if (ret)
> > +		dev_err(csi->dev, "Failed to stop subdev stream\n");
> > +
> > +	writel(0, csi->shim + SHIM_CNTL);
> > +
> > +	ret = dmaengine_terminate_sync(csi->dma.chan);
> > +	if (ret)
> > +		dev_err(csi->dev, "Failed to stop DMA\n");
> > +
> > +	writel(0, csi->shim + SHIM_DMACNTX);
> > +
> 
> Code from here...
> 
> > +	spin_lock_irqsave(&dma->lock, flags);
> > +	list_for_each_entry_safe(buf, tmp, &csi->dma.queue, list) {
> > +		list_del(&buf->list);
> > +		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> > +	}
> > +
> > +	if (dma->curr)
> > +		vb2_buffer_done(&dma->curr->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> > +
> > +	dma->curr = NULL;
> 
> ... to here could be moved to a separate function that takes a VB2 buf
> state parameter, to be also used in the error path of
> ti_csi2rx_start_streaming().

Ok.

> 
> > +	dma->state = TI_CSI2RX_DMA_STOPPED;
> > +	spin_unlock_irqrestore(&dma->lock, flags);
> > +}
> > +
> > +static const struct vb2_ops csi_vb2_qops = {
> > +	.queue_setup = ti_csi2rx_queue_setup,
> > +	.buf_prepare = ti_csi2rx_buffer_prepare,
> > +	.buf_queue = ti_csi2rx_buffer_queue,
> > +	.start_streaming = ti_csi2rx_start_streaming,
> > +	.stop_streaming = ti_csi2rx_stop_streaming,
> > +	.wait_prepare = vb2_ops_wait_prepare,
> > +	.wait_finish = vb2_ops_wait_finish,
> > +};
> > +
> > +static int ti_csi2rx_init_vb2q(struct ti_csi2rx_dev *csi)
> > +{
> > +	struct vb2_queue *q = &csi->vidq;
> > +	int ret;
> > +
> > +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > +	q->io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF | VB2_READ;
> 
> Usage of USERPTR and READ is not recommended, I'd drop them from the
> driver.
> 
> > +	q->drv_priv = csi;
> > +	q->buf_struct_size = sizeof(struct ti_csi2rx_buffer);
> > +	q->ops = &csi_vb2_qops;
> > +	q->mem_ops = &vb2_dma_contig_memops;
> > +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> > +	q->dev = dmaengine_get_dma_device(csi->dma.chan);
> 
> That's interesting, why do you use the dmaengine device and not csi->dev
> ?

Because it is the dmaengine device that transfers the data from CSI. CSI 
has no built in DMA.

> 
> > +	q->lock = &csi->mutex;
> > +
> > +	ret = vb2_queue_init(q);
> > +	if (ret)
> > +		return ret;
> > +
> > +	csi->vdev.queue = q;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_init_dma(struct ti_csi2rx_dev *csi)
> > +{
> > +	struct dma_slave_config cfg;
> 
> 	struct dma_slave_config cfg = { };
> 
> and you can drop the memset below. Or possibly even better,
> 
> 	struct dma_slave_config cfg = {
> 		.src_addr_with = DMA_SLAVE_BUSWIDTH_16_BYTES,
> 	};
> 
> > +	int ret;
> > +
> > +	INIT_LIST_HEAD(&csi->dma.queue);
> > +	spin_lock_init(&csi->dma.lock);
> > +
> > +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> > +
> > +	csi->dma.chan = dma_request_chan(csi->dev, "rx0");
> > +	if (IS_ERR(csi->dma.chan))
> > +		return PTR_ERR(csi->dma.chan);
> > +
> > +	memset(&cfg, 0, sizeof(cfg));
> > +
> > +	cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_16_BYTES;
> > +
> > +	ret = dmaengine_slave_config(csi->dma.chan, &cfg);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
> > +{
> > +	struct media_device *mdev = &csi->mdev;
> > +	struct video_device *vdev = &csi->vdev;
> > +	const struct ti_csi2rx_fmt *fmt;
> > +	struct v4l2_pix_format *pix_fmt = &csi->v_fmt.fmt.pix;
> > +	int ret;
> > +
> > +	fmt = find_format_by_pix(V4L2_PIX_FMT_UYVY);
> > +	if (!fmt)
> > +		return -EINVAL;
> > +
> > +	pix_fmt->width = 640;
> > +	pix_fmt->height = 480;
> 
> Should you initialize ->field too ?
> 
> > +
> > +	ti_csi2rx_fill_fmt(fmt, &csi->v_fmt);
> > +
> > +	mdev->dev = csi->dev;
> > +	mdev->hw_revision = 1;
> > +	strscpy(mdev->model, "TI-CSI2RX", sizeof(mdev->model));
> > +	snprintf(mdev->bus_info, sizeof(mdev->bus_info), "platform:%s",
> > +		 dev_name(mdev->dev));
> > +
> > +	media_device_init(mdev);
> > +
> > +	strscpy(vdev->name, TI_CSI2RX_MODULE_NAME, sizeof(vdev->name));
> > +	vdev->v4l2_dev = &csi->v4l2_dev;
> > +	vdev->vfl_dir = VFL_DIR_RX;
> > +	vdev->fops = &csi_fops;
> > +	vdev->ioctl_ops = &csi_ioctl_ops;
> > +	vdev->release = video_device_release_empty;
> > +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_READWRITE |
> 
> You can also drop V4L2_CAP_READWRITE if you drop VB2_READ above.
> 
> > +			    V4L2_CAP_STREAMING | V4L2_CAP_IO_MC;
> > +	vdev->lock = &csi->mutex;
> > +	video_set_drvdata(vdev, csi);
> > +
> > +	csi->pad.flags = MEDIA_PAD_FL_SINK;
> > +	ret = media_entity_pads_init(&csi->vdev.entity, 1, &csi->pad);
> > +	if (ret)
> > +		return ret;
> > +
> > +	csi->v4l2_dev.mdev = mdev;
> > +
> > +	ret = v4l2_device_register(csi->dev, &csi->v4l2_dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = media_device_register(mdev);
> > +	if (ret) {
> > +		v4l2_device_unregister(&csi->v4l2_dev);
> > +		media_device_cleanup(mdev);
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void ti_csi2rx_cleanup_dma(struct ti_csi2rx_dev *csi)
> > +{
> > +	dma_release_channel(csi->dma.chan);
> > +}
> > +
> > +static void ti_csi2rx_cleanup_v4l2(struct ti_csi2rx_dev *csi)
> > +{
> > +	media_device_unregister(&csi->mdev);
> > +	v4l2_device_unregister(&csi->v4l2_dev);
> > +	media_device_cleanup(&csi->mdev);
> > +}
> > +
> > +static void ti_csi2rx_cleanup_subdev(struct ti_csi2rx_dev *csi)
> > +{
> > +	v4l2_async_nf_unregister(&csi->notifier);
> > +	v4l2_async_nf_cleanup(&csi->notifier);
> > +}
> > +
> > +static void ti_csi2rx_cleanup_vb2q(struct ti_csi2rx_dev *csi)
> > +{
> > +	vb2_queue_release(&csi->vidq);
> > +}
> > +
> > +static int ti_csi2rx_probe(struct platform_device *pdev)
> > +{
> > +	struct ti_csi2rx_dev *csi;
> > +	struct resource *res;
> > +	int ret;
> > +
> > +	csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);
> 
> Don't use devm_kzalloc() here (see the explanation in the remove
> function).
> 
> > +	if (!csi)
> > +		return -ENOMEM;
> > +
> > +	csi->dev = &pdev->dev;
> > +	platform_set_drvdata(pdev, csi);
> > +
> > +	mutex_init(&csi->mutex);
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	csi->shim = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(csi->shim))
> > +		return PTR_ERR(csi->shim);
> > +
> > +	ret = ti_csi2rx_init_dma(csi);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = ti_csi2rx_v4l2_init(csi);
> > +	if (ret)
> > +		goto err_dma;
> > +
> > +	ret = ti_csi2rx_init_vb2q(csi);
> > +	if (ret)
> > +		goto err_v4l2;
> > +
> > +	ret = ti_csi2rx_init_subdev(csi);
> > +	if (ret)
> > +		goto err_vb2q;
> > +
> > +	ret = of_platform_populate(csi->dev->of_node, NULL, NULL, csi->dev);
> > +	if (ret) {
> > +		dev_err(csi->dev, "Failed to create children: %d\n", ret);
> > +		goto err_subdev;
> > +	}
> > +
> > +	return 0;
> > +
> > +err_subdev:
> > +	ti_csi2rx_cleanup_subdev(csi);
> > +err_vb2q:
> > +	ti_csi2rx_cleanup_vb2q(csi);
> > +err_v4l2:
> > +	ti_csi2rx_cleanup_v4l2(csi);
> > +err_dma:
> > +	ti_csi2rx_cleanup_dma(csi);
> > +	return ret;
> > +}
> > +
> > +static int ti_csi2rx_remove(struct platform_device *pdev)
> > +{
> > +	struct ti_csi2rx_dev *csi = platform_get_drvdata(pdev);
> > +
> > +	if (vb2_is_busy(&csi->vidq))
> > +		return -EBUSY;
> 
> That's not right, capture should instead be stopped.

Do you mean it should forcibly stop the ongoing capture by running 
ti_csi2rx_stop_streaming()?

> 
> The right way to handle this is to call all the unregister functions
> here, but not the cleanup functions, and to implement a real
> vdev->release handler that will perform all the cleanup and kfree() the
> ti_csi2rx_dev.

Is this some new convention? I see most drivers setting vdev->release to 
either video_device_release_empty or video_device_release. No one is 
freeing driver specific data in vdev->release.

And what if we have multiple video devices, like we would once
multiplexed streams are supported. Which vdev->release would free 
ti_csi2rx_dev then?

> 
> > +
> > +	video_unregister_device(&csi->vdev);
> > +
> > +	ti_csi2rx_cleanup_vb2q(csi);
> > +	ti_csi2rx_cleanup_subdev(csi);
> > +	ti_csi2rx_cleanup_v4l2(csi);
> > +	ti_csi2rx_cleanup_dma(csi);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id ti_csi2rx_of_match[] = {
> > +	{ .compatible = "ti,j721e-csi2rx", },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, ti_csi2rx_of_match);
> > +
> > +static struct platform_driver ti_csi2rx_pdrv = {
> > +	.probe = ti_csi2rx_probe,
> > +	.remove = ti_csi2rx_remove,
> > +	.driver = {
> > +		.name = TI_CSI2RX_MODULE_NAME,
> > +		.of_match_table = ti_csi2rx_of_match,
> > +	},
> > +};
> > +
> > +module_platform_driver(ti_csi2rx_pdrv);
> > +
> > +MODULE_DESCRIPTION("TI J721E CSI2 RX Driver");
> > +MODULE_AUTHOR("Pratyush Yadav <p.yadav@ti.com>");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_VERSION("1.0");
> 
> I'd drop the version, it will never change, so it's quite pointless. If
> userspace needs to know if the driver implements a particular feature or
> includes a bug fix, it can use the kernel version.

On Fri, 2022-01-21 at 19:58 +0530, Pratyush Yadav wrote:
> Hi,
> 
> This series adds support for CSI2 capture on J721E. It includes some
> fixes to the Cadence CSI2RX driver, re-structures the TI platform
> drivers, and finally adds the TI CSI2RX wrapper driver.
> 
> This series used to include the DPHY and DMA engine patches as well,
> but
> they have been split off to facilitate easier merging.
> 
> Tested on TI's J721E with OV5640 sensor.
> 
> The branch with all the patches needed to enable testing (dts nodes,
> OV5640 dropped patch, etc.) can be found here at
> https://github.com/prati0100/linux-next/ branch "capture".
> 

I've recently tried the patches from the above repo, ported forward to
kernel v6.0 on the AM625-SK with an OV5640 based camera. There were a
few things that I've had to patch up/hack to get it basically working,
the biggest probably being that (unlike the vendor driver provided for
this board) the CSI bridge gets set in 1x16 mode and the OV5640 driver
is hard coded to 2x8. I have a tree here:

https://gitlab.collabora.com/martyn/linux/-/commits/am625-sk-ov5640/

With the tree I've assembled I'm seeing capture failures a good
percentage of the time. I'm trying to capture a series of 10 still
images at the moment, the pipeline seems to get setup then no data
arrives (or at least it's not recognised). Killing it and rerunning
usually (eventually) works. I haven't dug into that yet.

Martyn

> Changes in v6:
> - Move the lock around the dereference for framefmt in
>   csi2rx_{get,set}_fmt() instead of when we get the pointer.
> - Do not return an error when an unsupported format is set. Instead
>   adjust the code to the first format in the list.
> - Drop variable bpp and use fmt->bpp directly.
> - Drop variable got_pm. Call phy_pm_runtime_put() unconditionally
> since
>   it will just return an error if runtime PM is not enabled.
> - Drop transcoding from the commit message.
> - Make csi2rx_media_ops const.
> 
> Changes in v5:
> - Cleanup notifier in csi2rx_parse_dt() after the call to
>   v4l2_async_nf_add_fwnode_remote().
> - Use YUV 1X16 formats instead of 2X8.
> - Only error out when phy_pm_runtime_get_sync() returns a negative
>   value. A positive value can be returned if the phy was already
>   resumed.
> - Do not query the source subdev for format. Use the newly added
>   internal format instead.
> - Make i unsigned.
> - Change %d to %u
> - Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
>   since the Rx mode DPHY now has a separate driver.
> - Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be
> done
>   at media_pipeline_start().
> - Do not assign flags.
> - Fix error handling in ti_csi2rx_start_streaming(). Free up vb2
> buffers
>   when media_pipeline_start() fails.
> - Move clock description in comments under the clocks property.
> - Make ports required.
> - Add link validation to cdns-csi2rx driver.
> 
> Changes in v4:
> - Drop the call to set PHY submode. It is now being done via
> compatible
>   on the DPHY side.
> - Acquire the media device's graph_mutex before starting the graph
> walk.
> - Call media_graph_walk_init() and media_graph_walk_cleanup() when
>   starting and ending the graph walk respectively.
> - Reduce max frame height and width in enum_framesizes. Currently
> they
>   are set to UINT_MAX but they must be a multiple of step_width, so
> they
>   need to be rounded down. Also, these values are absurdly large
> which
>   causes some userspace applications like gstreamer to trip up. While
> it
>   is not generally right to change the kernel for an application bug,
> it
>   is not such a big deal here. This change is replacing one set of
>   absurdly large arbitrary values with another set of smaller but
> still
>   absurdly large arbitrary values. Both limits are unlikely to be hit
> in
>   practice.
> - Add power-domains property.
> - Drop maxItems from clock-names.
> - Drop the type for data-lanes.
> - Drop uniqueItems from data-lanes. Move it to video-interfaces.yaml
>   instead.
> - Drop OV5640 runtime pm patch. It seems to be a bit complicated and
> it
>   is not exactly necessary for this series. Any CSI-2 camera will
> work
>   just fine, OV5640 just happens to be the one I tested with. I don't
>   want it to block this series. I will submit it as a separate patch
>   later.
> 
> Changes in v3:
> - Use v4l2_get_link_freq() to calculate pixel clock.
> - Move DMA related fields in struct ti_csi2rx_dma.
> - Protect DMA buffer queue with a spinlock to make sure the queue
> buffer
>   and DMA callback don't race on it.
> - Track the current DMA state. It might go idle because of a lack of
>   buffers. This state can be used to restart it if needed.
> - Do not include the current buffer in the pending queue. It is
> slightly
>   better modelling than leaving it at the head of the pending queue.
> - Use the buffer as the callback argument, and add a reference to csi
> in it.
> - If queueing a buffer to DMA fails, the buffer gets leaked and DMA
> gets
>   stalled with. Instead, report the error to vb2 and queue the next
>   buffer in the pending queue.
> - DMA gets stalled if we run out of buffers since the callback is the
>   only one that fires subsequent transfers and it is no longer being
>   called. Check for that when queueing buffers and restart DMA if
>   needed.
> - Do not put of node until we are done using the fwnode.
> - Set inital format to UYVY 640x480.
> - Add compatible: contains: const: cdns,csi2rx to allow SoC specific
>   compatible.
> - Add more constraints for data-lanes property.
> 
> Changes in v2:
> - Use phy_pm_runtime_get_sync() and phy_pm_runtime_put() before
> making
>   calls to set PHY mode, etc. to make sure it is ready.
> - Use dmaengine_get_dma_device() instead of directly accessing
>   dma->device->dev.
> - Do not set dst_addr_width when configuring slave DMA.
> - Move to a separate subdir and rename to j721e-csi2rx.c
> - Convert compatible to ti,j721e-csi2rx.
> - Move to use Media Controller centric APIs.
> - Improve cleanup in probe when one of the steps fails.
> - Add colorspace to formats database.
> - Set hw_revision on media_device.
> - Move video device initialization to probe time instead of register
> time.
> - Rename to ti,j721e-csi2rx.yaml
> - Add an entry in MAINTAINERS.
> - Add a description for the binding.
> - Change compatible to ti,j721e-csi2rx to make it SoC specific.
> - Remove description from dmas, reg, power-domains.
> - Remove a limit of 2 from #address-cells and #size-cells.
> - Fix add ^ to csi-bridge subnode regex.
> - Make ranges mandatory.
> - Add unit address in example.
> - Add a reference to cdns,csi2rx in csi-bridge subnode.
> - Expand the example to include the csi-bridge subnode as well.
> - Re-order subject prefixes.
> - Convert OV5640 to use runtime PM and drop Cadence CSI2RX s_power
> patch.
> - Drop subdev call wrappers from cdns-csi2rx.
> - Move VPE and CAL to a separate subdir.
> - Rename ti-csi2rx.c to j721e-csi2rx.c
> 
> Pratyush Yadav (14):
>   media: cadence: csi2rx: Unregister v4l2 async notifier
>   media: cadence: csi2rx: Cleanup media entity properly
>   media: cadence: csi2rx: Add get_fmt and set_fmt pad ops
>   media: cadence: csi2rx: Add external DPHY support
>   media: cadence: csi2rx: Soft reset the streams before starting
> capture
>   media: cadence: csi2rx: Set the STOP bit when stopping a stream
>   media: cadence: csi2rx: Fix stream data configuration
>   media: cadence: csi2rx: Populate subdev devnode
>   media: cadence: csi2rx: Add link validation
>   media: Re-structure TI platform drivers
>   media: ti: Add CSI2RX support for J721E
>   media: dt-bindings: Make sure items in data-lanes are unique
>   media: dt-bindings: Add DT bindings for TI J721E CSI2RX driver
>   media: dt-bindings: Convert Cadence CSI2RX binding to YAML
> 
>  .../devicetree/bindings/media/cdns,csi2rx.txt | 100 --
>  .../bindings/media/cdns,csi2rx.yaml           | 176 ++++
>  .../bindings/media/ti,j721e-csi2rx.yaml       | 101 ++
>  .../bindings/media/video-interfaces.yaml      |   1 +
>  MAINTAINERS                                   |  10 +-
>  drivers/media/platform/Kconfig                |  12 +
>  drivers/media/platform/Makefile               |   2 +-
>  drivers/media/platform/cadence/cdns-csi2rx.c  | 274 +++++-
>  drivers/media/platform/ti/Makefile            |   4 +
>  drivers/media/platform/ti/cal/Makefile        |   3 +
>  .../{ti-vpe => ti/cal}/cal-camerarx.c         |   0
>  .../platform/{ti-vpe => ti/cal}/cal-video.c   |   0
>  .../media/platform/{ti-vpe => ti/cal}/cal.c   |   0
>  .../media/platform/{ti-vpe => ti/cal}/cal.h   |   0
>  .../platform/{ti-vpe => ti/cal}/cal_regs.h    |   0
>  .../media/platform/ti/j721e-csi2rx/Makefile   |   2 +
>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 913
> ++++++++++++++++++
>  .../platform/{ti-vpe => ti/vpe}/Makefile      |   4 -
>  .../media/platform/{ti-vpe => ti/vpe}/csc.c   |   0
>  .../media/platform/{ti-vpe => ti/vpe}/csc.h   |   0
>  .../media/platform/{ti-vpe => ti/vpe}/sc.c    |   0
>  .../media/platform/{ti-vpe => ti/vpe}/sc.h    |   0
>  .../platform/{ti-vpe => ti/vpe}/sc_coeff.h    |   0
>  .../media/platform/{ti-vpe => ti/vpe}/vpdma.c |   0
>  .../media/platform/{ti-vpe => ti/vpe}/vpdma.h |   0
>  .../platform/{ti-vpe => ti/vpe}/vpdma_priv.h  |   0
>  .../media/platform/{ti-vpe => ti/vpe}/vpe.c   |   0
>  .../platform/{ti-vpe => ti/vpe}/vpe_regs.h    |   0
>  28 files changed, 1481 insertions(+), 121 deletions(-)
>  delete mode 100644
> Documentation/devicetree/bindings/media/cdns,csi2rx.txt
>  create mode 100644
> Documentation/devicetree/bindings/media/cdns,csi2rx.yaml
>  create mode 100644 Documentation/devicetree/bindings/media/ti,j721e-
> csi2rx.yaml
>  create mode 100644 drivers/media/platform/ti/Makefile
>  create mode 100644 drivers/media/platform/ti/cal/Makefile
>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal-camerarx.c
> (100%)
>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal-video.c (100%)
>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal.c (100%)
>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal.h (100%)
>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal_regs.h (100%)
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-
> csi2rx.c
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/Makefile (78%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/csc.c (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/csc.h (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/sc.c (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/sc.h (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/sc_coeff.h (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma.c (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma.h (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma_priv.h (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpe.c (100%)
>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpe_regs.h (100%)
>

Hi Martyn, all,

On 09/11/22 22:27, Martyn Welch wrote:
> On Fri, 2022-01-21 at 19:58 +0530, Pratyush Yadav wrote:
>> Hi,
>>
>> This series adds support for CSI2 capture on J721E. It includes some
>> fixes to the Cadence CSI2RX driver, re-structures the TI platform
>> drivers, and finally adds the TI CSI2RX wrapper driver.
>>
>> This series used to include the DPHY and DMA engine patches as well,
>> but
>> they have been split off to facilitate easier merging.
>>
>> Tested on TI's J721E with OV5640 sensor.
>>
>> The branch with all the patches needed to enable testing (dts nodes,
>> OV5640 dropped patch, etc.) can be found here at
>> https://github.com/prati0100/linux-next/ branch "capture".
>>
> 
> I've recently tried the patches from the above repo, ported forward to
> kernel v6.0 on the AM625-SK with an OV5640 based camera. There were a
> few things that I've had to patch up/hack to get it basically working,
> the biggest probably being that (unlike the vendor driver provided for
> this board) the CSI bridge gets set in 1x16 mode and the OV5640 driver
> is hard coded to 2x8. I have a tree here:
> 
> https://gitlab.collabora.com/martyn/linux/-/commits/am625-sk-ov5640/
> 
> With the tree I've assembled I'm seeing capture failures a good
> percentage of the time. I'm trying to capture a series of 10 still
> images at the moment, the pipeline seems to get setup then no data
> arrives (or at least it's not recognised). Killing it and rerunning
> usually (eventually) works. I haven't dug into that yet.
> 

Apologies for the delay in response and following up, since Pratyush moved out
of TI last year, I will be working on upstreaming and following up on this
series, I have posted a V7 of the series with pending feedback addressed,

https://lore.kernel.org/all/20230314115516.667-1-vaishnav.a@ti.com/

In the above version, streaming is working and tested on J721E-EVM and AM62-SK
with OV5640 without any issues, in your branch some of the patches are needed
for proper working especially the DPHY reset support, when Pratyush upstreamed
the series initially, the primary device used for testing was J721E Silicon
Revision 1.0, for all newer devices the below patch is also needed:

https://lore.kernel.org/all/20230314073137.2153-1-vaishnav.a@ti.com/

Thanks and Regards,
Vaishnav


> Martyn
> 
>> Changes in v6:
>> - Move the lock around the dereference for framefmt in
>>   csi2rx_{get,set}_fmt() instead of when we get the pointer.
>> - Do not return an error when an unsupported format is set. Instead
>>   adjust the code to the first format in the list.
>> - Drop variable bpp and use fmt->bpp directly.
>> - Drop variable got_pm. Call phy_pm_runtime_put() unconditionally
>> since
>>   it will just return an error if runtime PM is not enabled.
>> - Drop transcoding from the commit message.
>> - Make csi2rx_media_ops const.
>>
>> Changes in v5:
>> - Cleanup notifier in csi2rx_parse_dt() after the call to
>>   v4l2_async_nf_add_fwnode_remote().
>> - Use YUV 1X16 formats instead of 2X8.
>> - Only error out when phy_pm_runtime_get_sync() returns a negative
>>   value. A positive value can be returned if the phy was already
>>   resumed.
>> - Do not query the source subdev for format. Use the newly added
>>   internal format instead.
>> - Make i unsigned.
>> - Change %d to %u
>> - Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
>>   since the Rx mode DPHY now has a separate driver.
>> - Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be
>> done
>>   at media_pipeline_start().
>> - Do not assign flags.
>> - Fix error handling in ti_csi2rx_start_streaming(). Free up vb2
>> buffers
>>   when media_pipeline_start() fails.
>> - Move clock description in comments under the clocks property.
>> - Make ports required.
>> - Add link validation to cdns-csi2rx driver.
>>
>> Changes in v4:
>> - Drop the call to set PHY submode. It is now being done via
>> compatible
>>   on the DPHY side.
>> - Acquire the media device's graph_mutex before starting the graph
>> walk.
>> - Call media_graph_walk_init() and media_graph_walk_cleanup() when
>>   starting and ending the graph walk respectively.
>> - Reduce max frame height and width in enum_framesizes. Currently
>> they
>>   are set to UINT_MAX but they must be a multiple of step_width, so
>> they
>>   need to be rounded down. Also, these values are absurdly large
>> which
>>   causes some userspace applications like gstreamer to trip up. While
>> it
>>   is not generally right to change the kernel for an application bug,
>> it
>>   is not such a big deal here. This change is replacing one set of
>>   absurdly large arbitrary values with another set of smaller but
>> still
>>   absurdly large arbitrary values. Both limits are unlikely to be hit
>> in
>>   practice.
>> - Add power-domains property.
>> - Drop maxItems from clock-names.
>> - Drop the type for data-lanes.
>> - Drop uniqueItems from data-lanes. Move it to video-interfaces.yaml
>>   instead.
>> - Drop OV5640 runtime pm patch. It seems to be a bit complicated and
>> it
>>   is not exactly necessary for this series. Any CSI-2 camera will
>> work
>>   just fine, OV5640 just happens to be the one I tested with. I don't
>>   want it to block this series. I will submit it as a separate patch
>>   later.
>>
>> Changes in v3:
>> - Use v4l2_get_link_freq() to calculate pixel clock.
>> - Move DMA related fields in struct ti_csi2rx_dma.
>> - Protect DMA buffer queue with a spinlock to make sure the queue
>> buffer
>>   and DMA callback don't race on it.
>> - Track the current DMA state. It might go idle because of a lack of
>>   buffers. This state can be used to restart it if needed.
>> - Do not include the current buffer in the pending queue. It is
>> slightly
>>   better modelling than leaving it at the head of the pending queue.
>> - Use the buffer as the callback argument, and add a reference to csi
>> in it.
>> - If queueing a buffer to DMA fails, the buffer gets leaked and DMA
>> gets
>>   stalled with. Instead, report the error to vb2 and queue the next
>>   buffer in the pending queue.
>> - DMA gets stalled if we run out of buffers since the callback is the
>>   only one that fires subsequent transfers and it is no longer being
>>   called. Check for that when queueing buffers and restart DMA if
>>   needed.
>> - Do not put of node until we are done using the fwnode.
>> - Set inital format to UYVY 640x480.
>> - Add compatible: contains: const: cdns,csi2rx to allow SoC specific
>>   compatible.
>> - Add more constraints for data-lanes property.
>>
>> Changes in v2:
>> - Use phy_pm_runtime_get_sync() and phy_pm_runtime_put() before
>> making
>>   calls to set PHY mode, etc. to make sure it is ready.
>> - Use dmaengine_get_dma_device() instead of directly accessing
>>   dma->device->dev.
>> - Do not set dst_addr_width when configuring slave DMA.
>> - Move to a separate subdir and rename to j721e-csi2rx.c
>> - Convert compatible to ti,j721e-csi2rx.
>> - Move to use Media Controller centric APIs.
>> - Improve cleanup in probe when one of the steps fails.
>> - Add colorspace to formats database.
>> - Set hw_revision on media_device.
>> - Move video device initialization to probe time instead of register
>> time.
>> - Rename to ti,j721e-csi2rx.yaml
>> - Add an entry in MAINTAINERS.
>> - Add a description for the binding.
>> - Change compatible to ti,j721e-csi2rx to make it SoC specific.
>> - Remove description from dmas, reg, power-domains.
>> - Remove a limit of 2 from #address-cells and #size-cells.
>> - Fix add ^ to csi-bridge subnode regex.
>> - Make ranges mandatory.
>> - Add unit address in example.
>> - Add a reference to cdns,csi2rx in csi-bridge subnode.
>> - Expand the example to include the csi-bridge subnode as well.
>> - Re-order subject prefixes.
>> - Convert OV5640 to use runtime PM and drop Cadence CSI2RX s_power
>> patch.
>> - Drop subdev call wrappers from cdns-csi2rx.
>> - Move VPE and CAL to a separate subdir.
>> - Rename ti-csi2rx.c to j721e-csi2rx.c
>>
>> Pratyush Yadav (14):
>>   media: cadence: csi2rx: Unregister v4l2 async notifier
>>   media: cadence: csi2rx: Cleanup media entity properly
>>   media: cadence: csi2rx: Add get_fmt and set_fmt pad ops
>>   media: cadence: csi2rx: Add external DPHY support
>>   media: cadence: csi2rx: Soft reset the streams before starting
>> capture
>>   media: cadence: csi2rx: Set the STOP bit when stopping a stream
>>   media: cadence: csi2rx: Fix stream data configuration
>>   media: cadence: csi2rx: Populate subdev devnode
>>   media: cadence: csi2rx: Add link validation
>>   media: Re-structure TI platform drivers
>>   media: ti: Add CSI2RX support for J721E
>>   media: dt-bindings: Make sure items in data-lanes are unique
>>   media: dt-bindings: Add DT bindings for TI J721E CSI2RX driver
>>   media: dt-bindings: Convert Cadence CSI2RX binding to YAML
>>
>>  .../devicetree/bindings/media/cdns,csi2rx.txt | 100 --
>>  .../bindings/media/cdns,csi2rx.yaml           | 176 ++++
>>  .../bindings/media/ti,j721e-csi2rx.yaml       | 101 ++
>>  .../bindings/media/video-interfaces.yaml      |   1 +
>>  MAINTAINERS                                   |  10 +-
>>  drivers/media/platform/Kconfig                |  12 +
>>  drivers/media/platform/Makefile               |   2 +-
>>  drivers/media/platform/cadence/cdns-csi2rx.c  | 274 +++++-
>>  drivers/media/platform/ti/Makefile            |   4 +
>>  drivers/media/platform/ti/cal/Makefile        |   3 +
>>  .../{ti-vpe => ti/cal}/cal-camerarx.c         |   0
>>  .../platform/{ti-vpe => ti/cal}/cal-video.c   |   0
>>  .../media/platform/{ti-vpe => ti/cal}/cal.c   |   0
>>  .../media/platform/{ti-vpe => ti/cal}/cal.h   |   0
>>  .../platform/{ti-vpe => ti/cal}/cal_regs.h    |   0
>>  .../media/platform/ti/j721e-csi2rx/Makefile   |   2 +
>>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 913
>> ++++++++++++++++++
>>  .../platform/{ti-vpe => ti/vpe}/Makefile      |   4 -
>>  .../media/platform/{ti-vpe => ti/vpe}/csc.c   |   0
>>  .../media/platform/{ti-vpe => ti/vpe}/csc.h   |   0
>>  .../media/platform/{ti-vpe => ti/vpe}/sc.c    |   0
>>  .../media/platform/{ti-vpe => ti/vpe}/sc.h    |   0
>>  .../platform/{ti-vpe => ti/vpe}/sc_coeff.h    |   0
>>  .../media/platform/{ti-vpe => ti/vpe}/vpdma.c |   0
>>  .../media/platform/{ti-vpe => ti/vpe}/vpdma.h |   0
>>  .../platform/{ti-vpe => ti/vpe}/vpdma_priv.h  |   0
>>  .../media/platform/{ti-vpe => ti/vpe}/vpe.c   |   0
>>  .../platform/{ti-vpe => ti/vpe}/vpe_regs.h    |   0
>>  28 files changed, 1481 insertions(+), 121 deletions(-)
>>  delete mode 100644
>> Documentation/devicetree/bindings/media/cdns,csi2rx.txt
>>  create mode 100644
>> Documentation/devicetree/bindings/media/cdns,csi2rx.yaml
>>  create mode 100644 Documentation/devicetree/bindings/media/ti,j721e-
>> csi2rx.yaml
>>  create mode 100644 drivers/media/platform/ti/Makefile
>>  create mode 100644 drivers/media/platform/ti/cal/Makefile
>>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal-camerarx.c
>> (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal-video.c (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal.c (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal.h (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/cal}/cal_regs.h (100%)
>>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
>>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-
>> csi2rx.c
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/Makefile (78%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/csc.c (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/csc.h (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/sc.c (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/sc.h (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/sc_coeff.h (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma.c (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma.h (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpdma_priv.h (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpe.c (100%)
>>  rename drivers/media/platform/{ti-vpe => ti/vpe}/vpe_regs.h (100%)
>>
> 
>