[v3,1/2] dt-bindings: display: msm: Add optional resets

Add an optional reference to the MDSS_CORE reset, which when specified
can be used by the implementation to reset the hardware blocks.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---

Resending these two patches again as I put "v2" in the subject, even though I
meant v3. Sorry about that.

Changes since v2:
- None

 .../devicetree/bindings/display/msm/dpu-qcm2290.yaml          | 4 ++++
 Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml | 4 ++++
 Documentation/devicetree/bindings/display/msm/dpu-sc7280.yaml | 4 ++++
 Documentation/devicetree/bindings/display/msm/dpu-sdm845.yaml | 4 ++++
 4 files changed, 16 insertions(+)

On Sat, 9 Apr 2022 at 00:05, Bjorn Andersson <bjorn.andersson@linaro.org> wrote:
>
> It's typical for the bootloader to bring up the display for showing a
> boot splash or efi framebuffer. But in some cases the kernel driver ends
> up only partially configuring (in particular) the DPU, which might
> result in e.g. that two different data paths attempts to push data to
> the interface - with resulting graphical artifacts.
>
> Naturally the end goal would be to inherit the bootloader's
> configuration and provide the user with a glitch free handover from the
> boot configuration to a running DPU.
>
> But as implementing seamless transition from the bootloader
> configuration to the running OS will be a considerable effort, start by
> simply resetting the entire MDSS to its power-on state, to avoid the
> partial configuration.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


> ---
>
> Changes since v2:
> - Move the reset before the probing of the children, to avoid issues if child
>   drivers touched hardware at probe time.
> - Extend reset assert time as the previous 1us showed reliability issues on
>   Lenovo Flex 5G.
>
>  drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c | 32 ++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c
> index b10ca505f9ac..6f921910d0e0 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c
> @@ -3,10 +3,12 @@
>   * Copyright (c) 2018, The Linux Foundation
>   */
>
> +#include <linux/delay.h>
>  #include <linux/irq.h>
>  #include <linux/irqchip.h>
>  #include <linux/irqdesc.h>
>  #include <linux/irqchip/chained_irq.h>
> +#include <linux/reset.h>
>  #include "dpu_kms.h"
>
>  #define to_dpu_mdss(x) container_of(x, struct dpu_mdss, base)
> @@ -197,6 +199,32 @@ static void dpu_mdss_destroy(struct msm_mdss *mdss)
>         dpu_mdss->mmio = NULL;
>  }
>
> +static int dpu_mdss_reset(struct device *dev)
> +{
> +       struct reset_control *reset;
> +
> +       reset = reset_control_get_optional_exclusive(dev, NULL);
> +       if (!reset) {
> +               /* Optional reset not specified */
> +               return 0;
> +       } else if (IS_ERR(reset)) {
> +               DPU_ERROR("failed to acquire mdss reset, ret=%ld", PTR_ERR(reset));
> +               return PTR_ERR(reset);
> +       }
> +
> +       reset_control_assert(reset);
> +       /*
> +        * Tests indicate that reset has to be held for some period of time,
> +        * make it one frame in a typical system
> +        */
> +       msleep(20);
> +       reset_control_deassert(reset);
> +
> +       reset_control_put(reset);
> +
> +       return 0;
> +}
> +
>  static const struct msm_mdss_funcs mdss_funcs = {
>         .enable = dpu_mdss_enable,
>         .disable = dpu_mdss_disable,
> @@ -210,6 +238,10 @@ int dpu_mdss_init(struct platform_device *pdev)
>         int ret;
>         int irq;
>
> +       ret = dpu_mdss_reset(&pdev->dev);
> +       if (ret)
> +               return ret;
> +
>         dpu_mdss = devm_kzalloc(&pdev->dev, sizeof(*dpu_mdss), GFP_KERNEL);
>         if (!dpu_mdss)
>                 return -ENOMEM;
> --
> 2.35.1
>

On Sat, 9 Apr 2022 at 00:05, Bjorn Andersson <bjorn.andersson@linaro.org> wrote:
>
> Add an optional reference to the MDSS_CORE reset, which when specified
> can be used by the implementation to reset the hardware blocks.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


> ---
>
> Resending these two patches again as I put "v2" in the subject, even though I
> meant v3. Sorry about that.
>
> Changes since v2:
> - None
>
>  .../devicetree/bindings/display/msm/dpu-qcm2290.yaml          | 4 ++++
>  Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml | 4 ++++
>  Documentation/devicetree/bindings/display/msm/dpu-sc7280.yaml | 4 ++++
>  Documentation/devicetree/bindings/display/msm/dpu-sdm845.yaml | 4 ++++
>  4 files changed, 16 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/display/msm/dpu-qcm2290.yaml b/Documentation/devicetree/bindings/display/msm/dpu-qcm2290.yaml
> index 6fb7e321f011..734d14de966d 100644
> --- a/Documentation/devicetree/bindings/display/msm/dpu-qcm2290.yaml
> +++ b/Documentation/devicetree/bindings/display/msm/dpu-qcm2290.yaml
> @@ -66,6 +66,10 @@ properties:
>    interconnect-names:
>      const: mdp0-mem
>
> +  resets:
> +    items:
> +      - description: MDSS_CORE reset
> +
>  patternProperties:
>    "^display-controller@[0-9a-f]+$":
>      type: object
> diff --git a/Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml b/Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml
> index 12a86b1ec1bc..b41991eaa454 100644
> --- a/Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml
> +++ b/Documentation/devicetree/bindings/display/msm/dpu-sc7180.yaml
> @@ -65,6 +65,10 @@ properties:
>    interconnect-names:
>      const: mdp0-mem
>
> +  resets:
> +    items:
> +      - description: MDSS_CORE reset
> +
>  patternProperties:
>    "^display-controller@[0-9a-f]+$":
>      type: object
> diff --git a/Documentation/devicetree/bindings/display/msm/dpu-sc7280.yaml b/Documentation/devicetree/bindings/display/msm/dpu-sc7280.yaml
> index fbeb931a026e..6e417d06fc79 100644
> --- a/Documentation/devicetree/bindings/display/msm/dpu-sc7280.yaml
> +++ b/Documentation/devicetree/bindings/display/msm/dpu-sc7280.yaml
> @@ -64,6 +64,10 @@ properties:
>    interconnect-names:
>      const: mdp0-mem
>
> +  resets:
> +    items:
> +      - description: MDSS_CORE reset
> +
>  patternProperties:
>    "^display-controller@[0-9a-f]+$":
>      type: object
> diff --git a/Documentation/devicetree/bindings/display/msm/dpu-sdm845.yaml b/Documentation/devicetree/bindings/display/msm/dpu-sdm845.yaml
> index 0dca4b3d66e4..1a42491efdbc 100644
> --- a/Documentation/devicetree/bindings/display/msm/dpu-sdm845.yaml
> +++ b/Documentation/devicetree/bindings/display/msm/dpu-sdm845.yaml
> @@ -57,6 +57,10 @@ properties:
>
>    ranges: true
>
> +  resets:
> +    items:
> +      - description: MDSS_CORE reset
> +
>  patternProperties:
>    "^display-controller@[0-9a-f]+$":
>      type: object
> --
> 2.35.1
>

On 08/04/2022 23:08, Bjorn Andersson wrote:
> Add an optional reference to the MDSS_CORE reset, which when specified
> can be used by the implementation to reset the hardware blocks.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
> 
> Resending these two patches again as I put "v2" in the subject, even though I
> meant v3. Sorry about that.
> 

I reviewed v2, so one here as well:

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>


Best regards,
Krzysztof