[v3,2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller

Add a driver for Macronix MX25F0A NAND controller.

Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
---
 drivers/mtd/nand/raw/Kconfig     |   6 +
 drivers/mtd/nand/raw/Makefile    |   1 +
 drivers/mtd/nand/raw/mxic_nand.c | 294 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 301 insertions(+)
 create mode 100644 drivers/mtd/nand/raw/mxic_nand.c

Hi Mason,

Mason Yang <masonccyang@mxic.com.tw> wrote on Mon, 15 Apr 2019 17:23:52
+0800:

> Add a driver for Macronix MX25F0A NAND controller.
> 
> Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
> ---
>  drivers/mtd/nand/raw/Kconfig     |   6 +
>  drivers/mtd/nand/raw/Makefile    |   1 +
>  drivers/mtd/nand/raw/mxic_nand.c | 294 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 301 insertions(+)
>  create mode 100644 drivers/mtd/nand/raw/mxic_nand.c
> 
> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> index e604625..e0329cc 100644
> --- a/drivers/mtd/nand/raw/Kconfig
> +++ b/drivers/mtd/nand/raw/Kconfig
> @@ -522,6 +522,12 @@ config MTD_NAND_QCOM
>  	  Enables support for NAND flash chips on SoCs containing the EBI2 NAND
>  	  controller. This controller is found on IPQ806x SoC.
>  
> +config MTD_NAND_MXIC
> +	tristate "Macronix MX25F0A NAND controller"
> +	depends on HAS_IOMEM
> +	help
> +	  This selects the Macronix MX25F0A NAND controller driver.
> +
>  config MTD_NAND_MTK
>  	tristate "Support for NAND controller on MTK SoCs"
>  	depends on ARCH_MEDIATEK || COMPILE_TEST
> diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
> index 5a5a72f..c8a6790 100644
> --- a/drivers/mtd/nand/raw/Makefile
> +++ b/drivers/mtd/nand/raw/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_MTD_NAND_SUNXI)		+= sunxi_nand.o
>  obj-$(CONFIG_MTD_NAND_HISI504)	        += hisi504_nand.o
>  obj-$(CONFIG_MTD_NAND_BRCMNAND)		+= brcmnand/
>  obj-$(CONFIG_MTD_NAND_QCOM)		+= qcom_nandc.o
> +obj-$(CONFIG_MTD_NAND_MXIC)		+= mxic_nand.o
>  obj-$(CONFIG_MTD_NAND_MTK)		+= mtk_ecc.o mtk_nand.o
>  obj-$(CONFIG_MTD_NAND_TEGRA)		+= tegra_nand.o
>  obj-$(CONFIG_MTD_NAND_STM32_FMC2)	+= stm32_fmc2_nand.o
> diff --git a/drivers/mtd/nand/raw/mxic_nand.c b/drivers/mtd/nand/raw/mxic_nand.c
> new file mode 100644
> index 0000000..689fae2
> --- /dev/null
> +++ b/drivers/mtd/nand/raw/mxic_nand.c
> @@ -0,0 +1,294 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Copyright (C) 2019 Macronix International Co., Ltd.
> +//
> +// Authors:
> +//	Mason Yang <masonccyang@mxic.com.tw>
> +//	zhengxunli <zhengxunli@mxic.com.tw>

This is not a valid name.

Also if he appears here I suppose he should be credited in the
module_authors() macro too.

> +//

As a personal taste, I prefer when the header uses /* */ and only the
SPDX tag uses //.

> +
> +#include <linux/mfd/mxic-mx25f0a.h>
> +#include <linux/mtd/rawnand.h>
> +#include <linux/mtd/nand_ecc.h>
> +
> +#include "internals.h"
> +
> +struct mxic_nand_ctlr {
> +	struct mx25f0a_mfd *mfd;
> +	struct nand_controller base;
> +	struct nand_chip nand;

Even if this controller only supports one CS (and then, one chip),
please have a clear separation between the NAND controller and the NAND
chip by having one structure for the NAND chips and one structure for
the NAND controller.

> +};
> +
> +static void mxic_host_init(struct mxic_nand_ctlr *mxic)

Please choose a constant prefix for all functions, right now there is:
mxic_
mxic_nand_
mx25f0a_nand_

I think mxic_nand_ or mx25f0a_nand_ is wise.

> +{
> +	writel(DATA_STROB_EDO_EN, mxic->mfd->regs + DATA_STROB);
> +	writel(INT_STS_ALL, mxic->mfd->regs + INT_STS_EN);
> +	writel(0x0, mxic->mfd->regs + ONFI_DIN_CNT(0));
> +	writel(HC_CFG_NIO(8) | HC_CFG_SLV_ACT(0) | HC_CFG_IDLE_SIO_LVL(1) |
> +	       HC_CFG_TYPE(1, HC_CFG_TYPE_RAW_NAND) | HC_CFG_MAN_CS_EN,
> +	       mxic->mfd->regs + HC_CFG);
> +	writel(0x0, mxic->mfd->regs + HC_EN);
> +}
> +
> +static int  mxic_nand_wait_ready(struct nand_chip *chip)
> +{
> +	struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> +	u32 sts;
> +
> +	return readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> +				  sts & INT_RDY_PIN, 0, USEC_PER_SEC);
> +}
> +
> +static void mxic_nand_select_chip(struct nand_chip *chip, int chipnr)

_select_target() is preferred now

> +{
> +	struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> +
> +	switch (chipnr) {
> +	case 0:
> +	case 1:
> +		writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> +		writel(HC_CFG_MAN_CS_ASSERT | readl(mxic->mfd->regs + HC_CFG),
> +		       mxic->mfd->regs + HC_CFG);

In both case I would prefer a:

        reg = readl(...);
        reg &= ~xxx;
	reg |= yyy;
	writel(reg, ...);

Much easier to read.

> +		break;
> +
> +	case -1:
> +		writel(~HC_CFG_MAN_CS_ASSERT & readl(mxic->mfd->regs + HC_CFG),
> +		       mxic->mfd->regs + HC_CFG);
> +		writel(0, mxic->mfd->regs + HC_EN);
> +		break;
> +
> +	default:

Error?

> +		break;
> +	}
> +}
> +
> +static int mxic_nand_data_xfer(struct mxic_nand_ctlr *mxic, const void *txbuf,
> +			       void *rxbuf, unsigned int len)
> +{

There is not so much code shared, why not separating this function for
rx and tx cases?

> +	unsigned int pos = 0;
> +
> +	while (pos < len) {
> +		unsigned int nbytes = len - pos;
> +		u32 data = 0xffffffff;
> +		u32 sts;
> +		int ret;
> +
> +		if (nbytes > 4)
> +			nbytes = 4;
> +
> +		if (txbuf)
> +			memcpy(&data, txbuf + pos, nbytes);
> +
> +		ret = readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> +					 sts & INT_TX_EMPTY, 0, USEC_PER_SEC);

Using USEC_PER_SEC for a delay is weird

> +		if (ret)
> +			return ret;
> +
> +		writel(data, mxic->mfd->regs + TXD(nbytes % 4));
> +
> +		if (rxbuf) {
> +			ret = readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> +						 sts & INT_TX_EMPTY, 0,
> +						 USEC_PER_SEC);
> +			if (ret)
> +				return ret;
> +
> +			ret = readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> +						 sts & INT_RX_NOT_EMPTY, 0,
> +						 USEC_PER_SEC);
> +			if (ret)
> +				return ret;
> +
> +			data = readl(mxic->mfd->regs + RXD);
> +			data >>= (8 * (4 - nbytes));

What is this? Are you trying to handle some endianness issue?

> +			memcpy(rxbuf + pos, &data, nbytes);
> +			WARN_ON(readl(mxic->mfd->regs + INT_STS) &
> +				INT_RX_NOT_EMPTY);
> +		} else {
> +			readl(mxic->mfd->regs + RXD);
> +		}
> +		WARN_ON(readl(mxic->mfd->regs + INT_STS) & INT_RX_NOT_EMPTY);
> +
> +		pos += nbytes;
> +	}
> +
> +	return 0;
> +}
> +
> +static int mxic_nand_exec_op(struct nand_chip *chip,
> +			     const struct nand_operation *op, bool check_only)
> +{
> +	struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> +	const struct nand_op_instr *instr = NULL;
> +	int i, len = 0, ret = 0;
> +	unsigned int op_id;
> +	unsigned char cmdcnt = 0, addr_cnt = 0, cmd_addr[8] = {0};
> +
> +	for (op_id = 0; op_id < op->ninstrs; op_id++) {
> +		instr = &op->instrs[op_id];
> +
> +		switch (instr->type) {
> +		case NAND_OP_CMD_INSTR:
> +			cmd_addr[len++] = instr->ctx.cmd.opcode;
> +			cmdcnt++;
> +			break;
> +
> +		case NAND_OP_ADDR_INSTR:
> +			for (i = 0; i < instr->ctx.addr.naddrs; i++)
> +				cmd_addr[len++] = instr->ctx.addr.addrs[i];
> +			addr_cnt = i;
> +			break;
> +
> +		case NAND_OP_DATA_IN_INSTR:
> +			break;
> +
> +		case NAND_OP_DATA_OUT_INSTR:
> +			writel(instr->ctx.data.len,
> +			       mxic->mfd->regs + ONFI_DIN_CNT(0));
> +			break;
> +
> +		case NAND_OP_WAITRDY_INSTR:
> +			break;
> +		}
> +	}
> +
> +	if (op_id == 5 && instr->type == NAND_OP_WAITRDY_INSTR) {
> +		/*
> +		 * In case cmd-addr-data-cmd-wait in a sequence,
> +		 * separate the 2'nd command, i.e,. nand_prog_page_op()
> +		 */

I think this is the kind of limitation that could be described very
easily with a nand_op_parser structure and used by
nand_op_parser_exec_op() (see marvell_nand.c).

> +		writel(OP_CMD_BUSW(OP_BUSW_8) | OP_ADDR_BUSW(OP_BUSW_8) |
> +		       OP_DATA_BUSW(OP_BUSW_8) | OP_DUMMY_CYC(0x3F) |
> +		       OP_ADDR_BYTES(addr_cnt) |
> +		       OP_CMD_BYTES(1), mxic->mfd->regs + SS_CTRL(0));
> +		writel(0, mxic->mfd->regs + HC_EN);
> +		writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> +
> +		mxic_nand_data_xfer(mxic, cmd_addr, NULL, len - 1);
> +
> +		mxic_nand_data_xfer(mxic, instr->ctx.data.buf.out, NULL,
> +				    instr->ctx.data.len);
> +
> +		writel(0, mxic->mfd->regs + HC_EN);
> +		writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> +		mxic_nand_data_xfer(mxic, &cmd_addr[--len], NULL, 1);
> +		ret = mxic_nand_wait_ready(chip);
> +		if (ret)
> +			goto err_out;
> +		return ret;
> +	}
> +
> +	if (len) {
> +		writel(OP_CMD_BUSW(OP_BUSW_8) | OP_ADDR_BUSW(OP_BUSW_8) |
> +		       OP_DATA_BUSW(OP_BUSW_8) | OP_DUMMY_CYC(0x3F) |
> +		       OP_ADDR_BYTES(addr_cnt) |
> +		       OP_CMD_BYTES(cmdcnt > 0 ? cmdcnt : 0),
> +		       mxic->mfd->regs + SS_CTRL(0));
> +		writel(0, mxic->mfd->regs + HC_EN);
> +		writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> +
> +		mxic_nand_data_xfer(mxic, cmd_addr, NULL, len);
> +	}
> +
> +	for (op_id = 0; op_id < op->ninstrs; op_id++) {
> +		instr = &op->instrs[op_id];
> +
> +		switch (instr->type) {
> +		case NAND_OP_CMD_INSTR:
> +		case NAND_OP_ADDR_INSTR:
> +			break;
> +
> +		case NAND_OP_DATA_IN_INSTR:
> +			writel(0x0, mxic->mfd->regs + ONFI_DIN_CNT(0));
> +			writel(readl(mxic->mfd->regs + SS_CTRL(0)) | OP_READ,
> +			       mxic->mfd->regs + SS_CTRL(0));
> +			mxic_nand_data_xfer(mxic, NULL, instr->ctx.data.buf.in,
> +					    instr->ctx.data.len);
> +			break;
> +
> +		case NAND_OP_DATA_OUT_INSTR:
> +			mxic_nand_data_xfer(mxic, instr->ctx.data.buf.out, NULL,
> +					    instr->ctx.data.len);
> +			break;
> +
> +		case NAND_OP_WAITRDY_INSTR:
> +			ret = mxic_nand_wait_ready(chip);
> +			if (ret)
> +				goto err_out;
> +			break;
> +		}
> +	}
> +
> +err_out:
> +	return ret;

Ditto, please return directly if there is nothing in the error path.

> +}
> +
> +static const struct nand_controller_ops mxic_nand_controller_ops = {
> +	.exec_op = mxic_nand_exec_op,
> +};
> +
> +static int mx25f0a_nand_probe(struct platform_device *pdev)
> +{
> +	struct mtd_info *mtd;
> +	struct mx25f0a_mfd *mfd = dev_get_drvdata(pdev->dev.parent);
> +	struct mxic_nand_ctlr *mxic;
> +	struct nand_chip *nand_chip;
> +	int err;
> +
> +	mxic = devm_kzalloc(&pdev->dev, sizeof(struct mxic_nand_ctlr),
> +			    GFP_KERNEL);

mxic for a NAND controller structure is probably not a name meaningful
enough.

> +	if (!mxic)
> +		return -ENOMEM;
> +
> +	nand_chip = &mxic->nand;
> +	mtd = nand_to_mtd(nand_chip);
> +	mtd->dev.parent = pdev->dev.parent;
> +	nand_chip->ecc.priv = NULL;
> +	nand_set_flash_node(nand_chip, pdev->dev.parent->of_node);
> +	nand_chip->priv = mxic;
> +
> +	mxic->mfd = mfd;
> +
> +	nand_chip->legacy.select_chip = mxic_nand_select_chip;

Please don't implement legacy interfaces. You can check in
marvell_nand.c how this is handled now:

b25251414f6e mtd: rawnand: marvell: Stop implementing ->select_chip()

> +	mxic->base.ops = &mxic_nand_controller_ops;
> +	nand_controller_init(&mxic->base);
> +	nand_chip->controller = &mxic->base;
> +
> +	mxic_host_init(mxic);
> +
> +	err = nand_scan(nand_chip, 1);
> +	if (err)
> +		goto fail;

You can return directly as there is nothing to clean in the error path.

> +
> +	err = mtd_device_register(mtd, NULL, 0);
> +	if (err)
> +		goto fail;

Ditto

> +
> +	platform_set_drvdata(pdev, mxic);
> +
> +	return 0;
> +fail:
> +	return err;
> +}
> +
> +static int mx25f0a_nand_remove(struct platform_device *pdev)
> +{
> +	struct mxic_nand_ctlr *mxic = platform_get_drvdata(pdev);
> +
> +	nand_release(&mxic->nand);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver mx25f0a_nand_driver = {
> +	.probe		= mx25f0a_nand_probe,

Please don't align '=' on tabs.

> +	.remove		= mx25f0a_nand_remove,
> +	.driver		= {
> +		.name	= "mxic-nand-ctlr",
> +	},
> +};
> +module_platform_driver(mx25f0a_nand_driver);

mx25f0a_nand_controller_driver would be better

> +
> +MODULE_AUTHOR("Mason Yang <masonccyang@mxic.com.tw>");
> +MODULE_DESCRIPTION("MX25F0A RAW NAND controller driver");
> +MODULE_LICENSE("GPL v2");

Thanks,
Miquèl

Hi Miquel,

> > +// SPDX-License-Identifier: GPL-2.0
> > +//
> > +// Copyright (C) 2019 Macronix International Co., Ltd.
> > +//
> > +// Authors:
> > +//   Mason Yang <masonccyang@mxic.com.tw>
> > +//   zhengxunli <zhengxunli@mxic.com.tw>
> 
> This is not a valid name.
> 
> Also if he appears here I suppose he should be credited in the
> module_authors() macro too.

I think Li should maintain this NAND driver later, 
anyway, I may remove him.

> 
> > +//
> 
> As a personal taste, I prefer when the header uses /* */ and only the
> SPDX tag uses //.

okay, only SPDX tag use //

> 
> > +
> > +#include <linux/mfd/mxic-mx25f0a.h>
> > +#include <linux/mtd/rawnand.h>
> > +#include <linux/mtd/nand_ecc.h>
> > +
> > +#include "internals.h"
> > +
> > +struct mxic_nand_ctlr {
> > +   struct mx25f0a_mfd *mfd;
> > +   struct nand_controller base;
> > +   struct nand_chip nand;
> 
> Even if this controller only supports one CS (and then, one chip),
> please have a clear separation between the NAND controller and the NAND
> chip by having one structure for the NAND chips and one structure for
> the NAND controller.

okay, will patch it.

> 
> > +};
> > +
> > +static void mxic_host_init(struct mxic_nand_ctlr *mxic)
> 
> Please choose a constant prefix for all functions, right now there is:
> mxic_
> mxic_nand_
> mx25f0a_nand_
> 
> I think mxic_nand_ or mx25f0a_nand_ is wise.

okay, will use mxic_nand_ as prefix. 

> 
> > +{
> > +   writel(DATA_STROB_EDO_EN, mxic->mfd->regs + DATA_STROB);
> > +   writel(INT_STS_ALL, mxic->mfd->regs + INT_STS_EN);
> > +   writel(0x0, mxic->mfd->regs + ONFI_DIN_CNT(0));
> > +   writel(HC_CFG_NIO(8) | HC_CFG_SLV_ACT(0) | HC_CFG_IDLE_SIO_LVL(1) 
|
> > +          HC_CFG_TYPE(1, HC_CFG_TYPE_RAW_NAND) | HC_CFG_MAN_CS_EN,
> > +          mxic->mfd->regs + HC_CFG);
> > +   writel(0x0, mxic->mfd->regs + HC_EN);
> > +}
> > +
> > +static int  mxic_nand_wait_ready(struct nand_chip *chip)
> > +{
> > +   struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> > +   u32 sts;
> > +
> > +   return readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> > +              sts & INT_RDY_PIN, 0, USEC_PER_SEC);
> > +}
> > +
> > +static void mxic_nand_select_chip(struct nand_chip *chip, int chipnr)
> 
> _select_target() is preferred now
> 
> > +{
> > +   struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> > +
> > +   switch (chipnr) {
> > +   case 0:
> > +   case 1:
> > +      writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> > +      writel(HC_CFG_MAN_CS_ASSERT | readl(mxic->mfd->regs + HC_CFG),
> > +             mxic->mfd->regs + HC_CFG);
> 
> In both case I would prefer a:
> 
>         reg = readl(...);
>         reg &= ~xxx;
>    reg |= yyy;
>    writel(reg, ...);
> 
> Much easier to read.
> 
> > +      break;
> > +
> > +   case -1:
> > +      writel(~HC_CFG_MAN_CS_ASSERT & readl(mxic->mfd->regs + HC_CFG),
> > +             mxic->mfd->regs + HC_CFG);
> > +      writel(0, mxic->mfd->regs + HC_EN);
> > +      break;
> > +
> > +   default:
> 
> Error?
> 
> > +      break;
> > +   }
> > +}
> > +
> > +static int mxic_nand_data_xfer(struct mxic_nand_ctlr *mxic, const 
void *txbuf,
> > +                void *rxbuf, unsigned int len)
> > +{
> 
> There is not so much code shared, why not separating this function for
> rx and tx cases?
> 
> > +   unsigned int pos = 0;
> > +
> > +   while (pos < len) {
> > +      unsigned int nbytes = len - pos;
> > +      u32 data = 0xffffffff;
> > +      u32 sts;
> > +      int ret;
> > +
> > +      if (nbytes > 4)
> > +         nbytes = 4;
> > +
> > +      if (txbuf)
> > +         memcpy(&data, txbuf + pos, nbytes);
> > +
> > +      ret = readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> > +                sts & INT_TX_EMPTY, 0, USEC_PER_SEC);
> 
> Using USEC_PER_SEC for a delay is weird
> 
> > +      if (ret)
> > +         return ret;
> > +
> > +      writel(data, mxic->mfd->regs + TXD(nbytes % 4));
> > +
> > +      if (rxbuf) {
> > +         ret = readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> > +                   sts & INT_TX_EMPTY, 0,
> > +                   USEC_PER_SEC);
> > +         if (ret)
> > +            return ret;
> > +
> > +         ret = readl_poll_timeout(mxic->mfd->regs + INT_STS, sts,
> > +                   sts & INT_RX_NOT_EMPTY, 0,
> > +                   USEC_PER_SEC);
> > +         if (ret)
> > +            return ret;
> > +
> > +         data = readl(mxic->mfd->regs + RXD);
> > +         data >>= (8 * (4 - nbytes));
> 
> What is this? Are you trying to handle some endianness issue?

yes,

> 
> > +         memcpy(rxbuf + pos, &data, nbytes);
> > +         WARN_ON(readl(mxic->mfd->regs + INT_STS) &
> > +            INT_RX_NOT_EMPTY);
> > +      } else {
> > +         readl(mxic->mfd->regs + RXD);
> > +      }
> > +      WARN_ON(readl(mxic->mfd->regs + INT_STS) & INT_RX_NOT_EMPTY);
> > +
> > +      pos += nbytes;
> > +   }
> > +
> > +   return 0;
> > +}






> > +
> > +static int mxic_nand_exec_op(struct nand_chip *chip,
> > +              const struct nand_operation *op, bool check_only)
> > +{
> > +   struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> > +   const struct nand_op_instr *instr = NULL;
> > +   int i, len = 0, ret = 0;
> > +   unsigned int op_id;
> > +   unsigned char cmdcnt = 0, addr_cnt = 0, cmd_addr[8] = {0};
> > +
> > +   for (op_id = 0; op_id < op->ninstrs; op_id++) {
> > +      instr = &op->instrs[op_id];
> > +
> > +      switch (instr->type) {
> > +      case NAND_OP_CMD_INSTR:
> > +         cmd_addr[len++] = instr->ctx.cmd.opcode;
> > +         cmdcnt++;
> > +         break;
> > +
> > +      case NAND_OP_ADDR_INSTR:
> > +         for (i = 0; i < instr->ctx.addr.naddrs; i++)
> > +            cmd_addr[len++] = instr->ctx.addr.addrs[i];
> > +         addr_cnt = i;
> > +         break;
> > +
> > +      case NAND_OP_DATA_IN_INSTR:
> > +         break;
> > +
> > +      case NAND_OP_DATA_OUT_INSTR:
> > +         writel(instr->ctx.data.len,
> > +                mxic->mfd->regs + ONFI_DIN_CNT(0));
> > +         break;
> > +
> > +      case NAND_OP_WAITRDY_INSTR:
> > +         break;
> > +      }
> > +   }
> > +
> > +   if (op_id == 5 && instr->type == NAND_OP_WAITRDY_INSTR) {
> > +      /*
> > +       * In case cmd-addr-data-cmd-wait in a sequence,
> > +       * separate the 2'nd command, i.e,. nand_prog_page_op()
> > +       */
> 
> I think this is the kind of limitation that could be described very
> easily with a nand_op_parser structure and used by
> nand_op_parser_exec_op() (see marvell_nand.c).

okay, thanks for your information.
Will check and patch it.

> 
> > +      writel(OP_CMD_BUSW(OP_BUSW_8) | OP_ADDR_BUSW(OP_BUSW_8) |
> > +             OP_DATA_BUSW(OP_BUSW_8) | OP_DUMMY_CYC(0x3F) |
> > +             OP_ADDR_BYTES(addr_cnt) |
> > +             OP_CMD_BYTES(1), mxic->mfd->regs + SS_CTRL(0));
> > +      writel(0, mxic->mfd->regs + HC_EN);
> > +      writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> > +
> > +      mxic_nand_data_xfer(mxic, cmd_addr, NULL, len - 1);
> > +
> > +      mxic_nand_data_xfer(mxic, instr->ctx.data.buf.out, NULL,
> > +                instr->ctx.data.len);
> > +
> > +      writel(0, mxic->mfd->regs + HC_EN);
> > +      writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> > +      mxic_nand_data_xfer(mxic, &cmd_addr[--len], NULL, 1);
> > +      ret = mxic_nand_wait_ready(chip);
> > +      if (ret)
> > +         goto err_out;
> > +      return ret;
> > +   }
> > +
> > +   if (len) {
> > +      writel(OP_CMD_BUSW(OP_BUSW_8) | OP_ADDR_BUSW(OP_BUSW_8) |
> > +             OP_DATA_BUSW(OP_BUSW_8) | OP_DUMMY_CYC(0x3F) |
> > +             OP_ADDR_BYTES(addr_cnt) |
> > +             OP_CMD_BYTES(cmdcnt > 0 ? cmdcnt : 0),
> > +             mxic->mfd->regs + SS_CTRL(0));
> > +      writel(0, mxic->mfd->regs + HC_EN);
> > +      writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> > +
> > +      mxic_nand_data_xfer(mxic, cmd_addr, NULL, len);
> > +   }
> > +
> > +   for (op_id = 0; op_id < op->ninstrs; op_id++) {
> > +      instr = &op->instrs[op_id];
> > +
> > +      switch (instr->type) {
> > +      case NAND_OP_CMD_INSTR:
> > +      case NAND_OP_ADDR_INSTR:
> > +         break;
> > +
> > +      case NAND_OP_DATA_IN_INSTR:
> > +         writel(0x0, mxic->mfd->regs + ONFI_DIN_CNT(0));
> > +         writel(readl(mxic->mfd->regs + SS_CTRL(0)) | OP_READ,
> > +                mxic->mfd->regs + SS_CTRL(0));
> > +         mxic_nand_data_xfer(mxic, NULL, instr->ctx.data.buf.in,
> > +                   instr->ctx.data.len);
> > +         break;
> > +
> > +      case NAND_OP_DATA_OUT_INSTR:
> > +         mxic_nand_data_xfer(mxic, instr->ctx.data.buf.out, NULL,
> > +                   instr->ctx.data.len);
> > +         break;
> > +
> > +      case NAND_OP_WAITRDY_INSTR:
> > +         ret = mxic_nand_wait_ready(chip);
> > +         if (ret)
> > +            goto err_out;
> > +         break;
> > +      }
> > +   }
> > +
> > +err_out:
> > +   return ret;
> 
> Ditto, please return directly if there is nothing in the error path.

okay

> 
> > +}
> > +
> > +static const struct nand_controller_ops mxic_nand_controller_ops = {
> > +   .exec_op = mxic_nand_exec_op,
> > +};
> > +
> > +static int mx25f0a_nand_probe(struct platform_device *pdev)
> > +{
> > +   struct mtd_info *mtd;
> > +   struct mx25f0a_mfd *mfd = dev_get_drvdata(pdev->dev.parent);
> > +   struct mxic_nand_ctlr *mxic;
> > +   struct nand_chip *nand_chip;
> > +   int err;
> > +
> > +   mxic = devm_kzalloc(&pdev->dev, sizeof(struct mxic_nand_ctlr),
> > +             GFP_KERNEL);
> 
> mxic for a NAND controller structure is probably not a name meaningful
> enough.

How about *fmc or *mxic_fmc ?

> 
> > +   if (!mxic)
> > +      return -ENOMEM;
> > +
> > +   nand_chip = &mxic->nand;
> > +   mtd = nand_to_mtd(nand_chip);
> > +   mtd->dev.parent = pdev->dev.parent;
> > +   nand_chip->ecc.priv = NULL;
> > +   nand_set_flash_node(nand_chip, pdev->dev.parent->of_node);
> > +   nand_chip->priv = mxic;
> > +
> > +   mxic->mfd = mfd;
> > +
> > +   nand_chip->legacy.select_chip = mxic_nand_select_chip;
> 
> Please don't implement legacy interfaces. You can check in
> marvell_nand.c how this is handled now:
> 
> b25251414f6e mtd: rawnand: marvell: Stop implementing ->select_chip()

got it, will check & patch.

> 
> > +   mxic->base.ops = &mxic_nand_controller_ops;
> > +   nand_controller_init(&mxic->base);
> > +   nand_chip->controller = &mxic->base;
> > +
> > +   mxic_host_init(mxic);
> > +
> > +   err = nand_scan(nand_chip, 1);
> > +   if (err)
> > +      goto fail;
> 
> You can return directly as there is nothing to clean in the error path.
> 
> > +
> > +   err = mtd_device_register(mtd, NULL, 0);
> > +   if (err)
> > +      goto fail;
> 
> Ditto
> 
> > +
> > +   platform_set_drvdata(pdev, mxic);
> > +
> > +   return 0;
> > +fail:
> > +   return err;
> > +}
> > +
> > +static int mx25f0a_nand_remove(struct platform_device *pdev)
> > +{
> > +   struct mxic_nand_ctlr *mxic = platform_get_drvdata(pdev);
> > +
> > +   nand_release(&mxic->nand);
> > +
> > +   return 0;
> > +}
> > +
> > +static struct platform_driver mx25f0a_nand_driver = {
> > +   .probe      = mx25f0a_nand_probe,
> 
> Please don't align '=' on tabs.

okay, will fix and also remove "mx25f0a" char.
patch to:
mxic_nand_driver & mxic_nand_probe.


thanks for your review.
best regards,
Mason

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Hi masonccyang@mxic.com.tw,

masonccyang@mxic.com.tw wrote on Wed, 15 May 2019 16:48:46 +0800:

> Hi Miquel,
> 
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +//
> > > +// Copyright (C) 2019 Macronix International Co., Ltd.
> > > +//
> > > +// Authors:
> > > +//   Mason Yang <masonccyang@mxic.com.tw>
> > > +//   zhengxunli <zhengxunli@mxic.com.tw>  
> > 
> > This is not a valid name.
> > 
> > Also if he appears here I suppose he should be credited in the
> > module_authors() macro too.  
> 
> I think Li should maintain this NAND driver later, 

This entry is for the authors of the driver.

If he will maintain the driver, then add a new entry in MAINTAINERS.

> > > +}
> > > +
> > > +static const struct nand_controller_ops mxic_nand_controller_ops = {
> > > +   .exec_op = mxic_nand_exec_op,
> > > +};
> > > +
> > > +static int mx25f0a_nand_probe(struct platform_device *pdev)
> > > +{
> > > +   struct mtd_info *mtd;
> > > +   struct mx25f0a_mfd *mfd = dev_get_drvdata(pdev->dev.parent);
> > > +   struct mxic_nand_ctlr *mxic;
> > > +   struct nand_chip *nand_chip;
> > > +   int err;
> > > +
> > > +   mxic = devm_kzalloc(&pdev->dev, sizeof(struct mxic_nand_ctlr),
> > > +             GFP_KERNEL);  
> > 
> > mxic for a NAND controller structure is probably not a name meaningful
> > enough.  
> 
> How about *fmc or *mxic_fmc ?

fmc is fine, even if I personally prefer nfc for NAND flash controller.
Here the 'm' in fmc stands for 'memory' but I am not sure if the
controller can manage something else than NAND flash anyway?


Thanks,
Miquèl

Hi Miquel,

> > +
> > +static void mxic_nand_select_chip(struct nand_chip *chip, int chipnr)
> 
> _select_target() is preferred now

Do you mean I implement mxic_nand_select_target() to control #CS ?

If so, I need to call mxic_nand_select_target( ) to control #CS ON
and then #CS OFF in _exec_op() due to nand_select_target()<in nand_base,c>
is still calling chip->legacy.select_chip ?

> 
> > +{
> > +   struct mxic_nand_ctlr *mxic = nand_get_controller_data(chip);
> > +
> > +   switch (chipnr) {
> > +   case 0:
> > +   case 1:
> > +      writel(HC_EN_BIT, mxic->mfd->regs + HC_EN);
> > +      writel(HC_CFG_MAN_CS_ASSERT | readl(mxic->mfd->regs + HC_CFG),
> > +             mxic->mfd->regs + HC_CFG);
> 
> In both case I would prefer a:
> 
>         reg = readl(...);
>         reg &= ~xxx;
>    reg |= yyy;
>    writel(reg, ...);
> 
> Much easier to read.
> 
> > +      break;
> > +
> > +   case -1:
> > +      writel(~HC_CFG_MAN_CS_ASSERT & readl(mxic->mfd->regs + HC_CFG),
> > +             mxic->mfd->regs + HC_CFG);
> > +      writel(0, mxic->mfd->regs + HC_EN);
> > +      break;
> > +
> > +   default:
> 
> Error?
> 
> > +      break;
> > +   }
> > +}
> > +

> > +static int mx25f0a_nand_probe(struct platform_device *pdev)
> > +{
> > +   struct mtd_info *mtd;
> > +   struct mx25f0a_mfd *mfd = dev_get_drvdata(pdev->dev.parent);
> > +   struct mxic_nand_ctlr *mxic;
> > +   struct nand_chip *nand_chip;
> > +   int err;
> > +
> > +   mxic = devm_kzalloc(&pdev->dev, sizeof(struct mxic_nand_ctlr),
> > +             GFP_KERNEL);
> 
> mxic for a NAND controller structure is probably not a name meaningful
> enough.
> 
> > +   if (!mxic)
> > +      return -ENOMEM;
> > +
> > +   nand_chip = &mxic->nand;
> > +   mtd = nand_to_mtd(nand_chip);
> > +   mtd->dev.parent = pdev->dev.parent;
> > +   nand_chip->ecc.priv = NULL;
> > +   nand_set_flash_node(nand_chip, pdev->dev.parent->of_node);
> > +   nand_chip->priv = mxic;
> > +
> > +   mxic->mfd = mfd;
> > +
> > +   nand_chip->legacy.select_chip = mxic_nand_select_chip;
> 
> Please don't implement legacy interfaces. You can check in
> marvell_nand.c how this is handled now:
> 
> b25251414f6e mtd: rawnand: marvell: Stop implementing ->select_chip()
> 

Does it mean chip->legacy.select_chip() will phase-out ?


thanks & best regards,
Mason

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=====================================================================

Hi Mason,

masonccyang@mxic.com.tw wrote on Fri, 17 May 2019 17:30:21 +0800:

> Hi Miquel,
> 
> > > +
> > > +static void mxic_nand_select_chip(struct nand_chip *chip, int chipnr)  
> > 
> > _select_target() is preferred now  
> 
> Do you mean I implement mxic_nand_select_target() to control #CS ?
> 
> If so, I need to call mxic_nand_select_target( ) to control #CS ON
> and then #CS OFF in _exec_op() due to nand_select_target()<in nand_base,c>
> is still calling chip->legacy.select_chip ?

You must forget about the ->select_chip() callback. Now it should be
handled directly from the controller driver. Please have a look at the
commit pointed against the marvell_nand.c driver.

[...]

> > > +   if (!mxic)
> > > +      return -ENOMEM;
> > > +
> > > +   nand_chip = &mxic->nand;
> > > +   mtd = nand_to_mtd(nand_chip);
> > > +   mtd->dev.parent = pdev->dev.parent;
> > > +   nand_chip->ecc.priv = NULL;
> > > +   nand_set_flash_node(nand_chip, pdev->dev.parent->of_node);
> > > +   nand_chip->priv = mxic;
> > > +
> > > +   mxic->mfd = mfd;
> > > +
> > > +   nand_chip->legacy.select_chip = mxic_nand_select_chip;  
> > 
> > Please don't implement legacy interfaces. You can check in
> > marvell_nand.c how this is handled now:
> > 
> > b25251414f6e mtd: rawnand: marvell: Stop implementing ->select_chip()
> >   
> 
> Does it mean chip->legacy.select_chip() will phase-out ?

Yes it will.

Thanks,
Miquèl

Hi Miquel,

> > 
> > > > +
> > > > +static void mxic_nand_select_chip(struct nand_chip *chip, int 
chipnr) 
> > > 
> > > _select_target() is preferred now 
> > 
> > Do you mean I implement mxic_nand_select_target() to control #CS ?
> > 
> > If so, I need to call mxic_nand_select_target( ) to control #CS ON
> > and then #CS OFF in _exec_op() due to nand_select_target()<in 
nand_base,c>
> > is still calling chip->legacy.select_chip ?
> 
> You must forget about the ->select_chip() callback. Now it should be
> handled directly from the controller driver. Please have a look at the
> commit pointed against the marvell_nand.c driver.

I have no Marvell NFC datasheet and have one question.

In marvell_nand.c, there is no xxx_deselect_target() or 
something like that doing #CS OFF.
marvell_nfc_select_target() seems always to make one of chip or die
#CS keep low.

Is it right ?

How to make all #CS keep high for NAND to enter 
low-power standby mode if driver don't use "legacy.select_chip()" ?

thanks & best regards,
Mason

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============================================================================

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Hi Mason,

masonccyang@mxic.com.tw wrote on Thu, 23 May 2019 16:58:02 +0800:

> Hi Miquel,
> 
> > >   
> > > > > +
> > > > > +static void mxic_nand_select_chip(struct nand_chip *chip, int   
> chipnr) 
> > > > 
> > > > _select_target() is preferred now   
> > > 
> > > Do you mean I implement mxic_nand_select_target() to control #CS ?
> > > 
> > > If so, I need to call mxic_nand_select_target( ) to control #CS ON
> > > and then #CS OFF in _exec_op() due to nand_select_target()<in   
> nand_base,c>  
> > > is still calling chip->legacy.select_chip ?  
> > 
> > You must forget about the ->select_chip() callback. Now it should be
> > handled directly from the controller driver. Please have a look at the
> > commit pointed against the marvell_nand.c driver.  
> 
> I have no Marvell NFC datasheet and have one question.
> 
> In marvell_nand.c, there is no xxx_deselect_target() or 
> something like that doing #CS OFF.
> marvell_nfc_select_target() seems always to make one of chip or die
> #CS keep low.
> 
> Is it right ?

Yes, AFAIR there is no "de-assert" mechanism in this controller.

> 
> How to make all #CS keep high for NAND to enter 
> low-power standby mode if driver don't use "legacy.select_chip()" ?

See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip() optional
when ->exec_op() is implemented") which states:

        "When [->select_chip() is] not implemented, the core is assuming
	the CS line is automatically asserted/deasserted by the driver
	->exec_op() implementation."

Of course, the above is right only when the controller driver supports
the ->exec_op() interface. 

So if you think it is not too time consuming and worth the trouble to
assert/deassert the CS at each operation, you may do it in your driver.


Thanks,
Miquèl

Hi Miquel,

> > > > > > +static void mxic_nand_select_chip(struct nand_chip *chip, int 
 
> > chipnr) 
> > > > > 
> > > > > _select_target() is preferred now 
> > > > 
> > > > Do you mean I implement mxic_nand_select_target() to control #CS ?
> > > > 
> > > > If so, I need to call mxic_nand_select_target( ) to control #CS ON
> > > > and then #CS OFF in _exec_op() due to nand_select_target()<in 
> > nand_base,c> 
> > > > is still calling chip->legacy.select_chip ? 
> > > 
> > > You must forget about the ->select_chip() callback. Now it should be
> > > handled directly from the controller driver. Please have a look at 
the
> > > commit pointed against the marvell_nand.c driver. 
> > 
> > I have no Marvell NFC datasheet and have one question.
> > 
> > In marvell_nand.c, there is no xxx_deselect_target() or 
> > something like that doing #CS OFF.
> > marvell_nfc_select_target() seems always to make one of chip or die
> > #CS keep low.
> > 
> > Is it right ?
> 
> Yes, AFAIR there is no "de-assert" mechanism in this controller.
> 
> > 
> > How to make all #CS keep high for NAND to enter 
> > low-power standby mode if driver don't use "legacy.select_chip()" ?
> 
> See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip() optional
> when ->exec_op() is implemented") which states:
> 
>         "When [->select_chip() is] not implemented, the core is assuming
>    the CS line is automatically asserted/deasserted by the driver
>    ->exec_op() implementation."
> 
> Of course, the above is right only when the controller driver supports
> the ->exec_op() interface. 

Currently, it seems that we will get the incorrect data and error
operation due to CS in error toggling if CS line is controlled in 
->exec_op().
i.e,. 

1) In nand_onfi_detect() to call nand_exec_op() twice by 
nand_read_param_page_op() and annd_read_data_op()

2) In nand_write_page_xxx to call nand_exec_op() many times by
nand_prog_page_begin_op(), nand_write_data_op() and 
nand_prog_page_end_op().


Should we consider to add a CS line controller in struct nand_controller
i.e,.

struct nand_controller {
         struct mutex lock;
         const struct nand_controller_ops *ops;
+          void (*select_chip)(struct nand_chip *chip, int cs);
};

to replace legacy.select_chip() ?


To patch in nand_select_target() and nand_deselect_target()

void nand_select_target(struct nand_chip *chip, unsigned int cs)
{
        /*
         * cs should always lie between 0 and chip->numchips, when that's 
not
         * the case it's a bug and the caller should be fixed.
         */
        if (WARN_ON(cs > chip->numchips))
                return;

        chip->cur_cs = cs;

+       if (chip->controller->select_chip)
+               chip->controller->select_chip(chip, cs);
+
        if (chip->legacy.select_chip)
                chip->legacy.select_chip(chip, cs);
}

void nand_deselect_target(struct nand_chip *chip)
{
+       if (chip->controller->select_chip)
+               chip->controller->select_chip(chip, -1);
+
        if (chip->legacy.select_chip)
                chip->legacy.select_chip(chip, -1);

        chip->cur_cs = -1;
}


> 
> So if you think it is not too time consuming and worth the trouble to
> assert/deassert the CS at each operation, you may do it in your driver.
> 
> 
> Thanks,
> Miquèl

thanks & best regards,
Mason

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Hi Mason,

masonccyang@mxic.com.tw wrote on Wed, 29 May 2019 11:12:08 +0800:

> Hi Miquel,
> 
> > > > > > > +static void mxic_nand_select_chip(struct nand_chip *chip, int   
>  
> > > chipnr)   
> > > > > > 
> > > > > > _select_target() is preferred now   
> > > > > 
> > > > > Do you mean I implement mxic_nand_select_target() to control #CS ?
> > > > > 
> > > > > If so, I need to call mxic_nand_select_target( ) to control #CS ON
> > > > > and then #CS OFF in _exec_op() due to nand_select_target()<in   
> > > nand_base,c>   
> > > > > is still calling chip->legacy.select_chip ?   
> > > > 
> > > > You must forget about the ->select_chip() callback. Now it should be
> > > > handled directly from the controller driver. Please have a look at   
> the
> > > > commit pointed against the marvell_nand.c driver.   
> > > 
> > > I have no Marvell NFC datasheet and have one question.
> > > 
> > > In marvell_nand.c, there is no xxx_deselect_target() or 
> > > something like that doing #CS OFF.
> > > marvell_nfc_select_target() seems always to make one of chip or die
> > > #CS keep low.
> > > 
> > > Is it right ?  
> > 
> > Yes, AFAIR there is no "de-assert" mechanism in this controller.
> >   
> > > 
> > > How to make all #CS keep high for NAND to enter 
> > > low-power standby mode if driver don't use "legacy.select_chip()" ?  
> > 
> > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip() optional
> > when ->exec_op() is implemented") which states:
> > 
> >         "When [->select_chip() is] not implemented, the core is assuming
> >    the CS line is automatically asserted/deasserted by the driver  
> >    ->exec_op() implementation."  
> > 
> > Of course, the above is right only when the controller driver supports
> > the ->exec_op() interface.   
> 
> Currently, it seems that we will get the incorrect data and error
> operation due to CS in error toggling if CS line is controlled in 
> ->exec_op().  

Most of the chips today are CS-don't-care, which chip are you using?

Is this behavior publicly documented?

Is this LPM mode always activated?

> i.e,. 
> 
> 1) In nand_onfi_detect() to call nand_exec_op() twice by 
> nand_read_param_page_op() and annd_read_data_op()
> 
> 2) In nand_write_page_xxx to call nand_exec_op() many times by
> nand_prog_page_begin_op(), nand_write_data_op() and 
> nand_prog_page_end_op().
> 
> 
> Should we consider to add a CS line controller in struct nand_controller
> i.e,.
> 
> struct nand_controller {
>          struct mutex lock;
>          const struct nand_controller_ops *ops;
> +          void (*select_chip)(struct nand_chip *chip, int cs);
> };
> 
> to replace legacy.select_chip() ?
> 

No, if really needed, we could add a "macro op done" flag in the nand
operation structure.


Thanks,
Miquèl

Hi Miquel,

> 
> > > > > > > > +static void mxic_nand_select_chip(struct nand_chip *chip, 
int 
> > 
> > > > chipnr) 
> > > > > > > 
> > > > > > > _select_target() is preferred now 
> > > > > > 
> > > > > > Do you mean I implement mxic_nand_select_target() to control 
#CS ?
> > > > > > 
> > > > > > If so, I need to call mxic_nand_select_target( ) to control 
#CS ON
> > > > > > and then #CS OFF in _exec_op() due to nand_select_target()<in  

> > > > nand_base,c> 
> > > > > > is still calling chip->legacy.select_chip ? 
> > > > > 
> > > > > You must forget about the ->select_chip() callback. Now it 
should be
> > > > > handled directly from the controller driver. Please have a look 
at 
> > the
> > > > > commit pointed against the marvell_nand.c driver. 
> > > > 
> > > > I have no Marvell NFC datasheet and have one question.
> > > > 
> > > > In marvell_nand.c, there is no xxx_deselect_target() or 
> > > > something like that doing #CS OFF.
> > > > marvell_nfc_select_target() seems always to make one of chip or 
die
> > > > #CS keep low.
> > > > 
> > > > Is it right ? 
> > > 
> > > Yes, AFAIR there is no "de-assert" mechanism in this controller.
> > > 
> > > > 
> > > > How to make all #CS keep high for NAND to enter 
> > > > low-power standby mode if driver don't use "legacy.select_chip()" 
? 
> > > 
> > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip() 
optional
> > > when ->exec_op() is implemented") which states:
> > > 
> > >         "When [->select_chip() is] not implemented, the core is 
assuming
> > >    the CS line is automatically asserted/deasserted by the driver 
> > >    ->exec_op() implementation." 
> > > 
> > > Of course, the above is right only when the controller driver 
supports
> > > the ->exec_op() interface. 
> > 
> > Currently, it seems that we will get the incorrect data and error
> > operation due to CS in error toggling if CS line is controlled in 
> > ->exec_op(). 
> 
> Most of the chips today are CS-don't-care, which chip are you using?

I think CS-don't-care means read-write operation for NAND device to reside
on the same memory bus as other Flash or SRAM devices. Other devices on 
the 
memory bus can then be accessed while the NAND Flash is busy with internal 

operations. This capability is very important for designs that require 
multiple
NAND Flash devices on the same bus.

> 
> Is this behavior publicly documented?
> 

CS# pin goes High enter standby mode to reduce power consumption,
i.e,. standby mode w/ CS# keep High, standby current: 10 uA (Typ for 3.3V 
NAND)
        otherwise, current is more than 1 mA.
i.e,. page read current, 25 mA (Typ for 3.3V NAND)
 

> Is this LPM mode always activated?
> 
> > i.e,. 
> > 
> > 1) In nand_onfi_detect() to call nand_exec_op() twice by 
> > nand_read_param_page_op() and annd_read_data_op()
> > 
> > 2) In nand_write_page_xxx to call nand_exec_op() many times by
> > nand_prog_page_begin_op(), nand_write_data_op() and 
> > nand_prog_page_end_op().
> > 
> > 
> > Should we consider to add a CS line controller in struct 
nand_controller
> > i.e,.
> > 
> > struct nand_controller {
> >          struct mutex lock;
> >          const struct nand_controller_ops *ops;
> > +          void (*select_chip)(struct nand_chip *chip, int cs);
> > };
> > 
> > to replace legacy.select_chip() ?
> > 
> 
> No, if really needed, we could add a "macro op done" flag in the nand
> operation structure.
> 

Is this "macron op done" flag good for multiple NAND devices on
the same bus ?

Any other way to control CS# pin? if user application is really
care of power consumption, i.e,. loT.

> 
> Thanks,
> Miquèl

thanks & best regards,
Mason

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Hi Mason,

On Tue, 18 Jun 2019 09:24:14 +0800
masonccyang@mxic.com.tw wrote:

> Hi Miquel,
> 
> >   
> > > > > > > > > +static void mxic_nand_select_chip(struct nand_chip *chip,   
> int 
> > >   
> > > > > chipnr)   
> > > > > > > > 
> > > > > > > > _select_target() is preferred now   
> > > > > > > 
> > > > > > > Do you mean I implement mxic_nand_select_target() to control   
> #CS ?
> > > > > > > 
> > > > > > > If so, I need to call mxic_nand_select_target( ) to control   
> #CS ON
> > > > > > > and then #CS OFF in _exec_op() due to nand_select_target()<in    
> 
> > > > > nand_base,c>   
> > > > > > > is still calling chip->legacy.select_chip ?   
> > > > > > 
> > > > > > You must forget about the ->select_chip() callback. Now it   
> should be
> > > > > > handled directly from the controller driver. Please have a look   
> at 
> > > the  
> > > > > > commit pointed against the marvell_nand.c driver.   
> > > > > 
> > > > > I have no Marvell NFC datasheet and have one question.
> > > > > 
> > > > > In marvell_nand.c, there is no xxx_deselect_target() or 
> > > > > something like that doing #CS OFF.
> > > > > marvell_nfc_select_target() seems always to make one of chip or   
> die
> > > > > #CS keep low.
> > > > > 
> > > > > Is it right ?   
> > > > 
> > > > Yes, AFAIR there is no "de-assert" mechanism in this controller.
> > > >   
> > > > > 
> > > > > How to make all #CS keep high for NAND to enter 
> > > > > low-power standby mode if driver don't use "legacy.select_chip()"   
> ? 
> > > > 
> > > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip()   
> optional
> > > > when ->exec_op() is implemented") which states:
> > > > 
> > > >         "When [->select_chip() is] not implemented, the core is   
> assuming
> > > >    the CS line is automatically asserted/deasserted by the driver   
> > > >    ->exec_op() implementation."   
> > > > 
> > > > Of course, the above is right only when the controller driver   
> supports
> > > > the ->exec_op() interface.   
> > > 
> > > Currently, it seems that we will get the incorrect data and error
> > > operation due to CS in error toggling if CS line is controlled in   
> > > ->exec_op().   
> > 
> > Most of the chips today are CS-don't-care, which chip are you using?  
> 
> I think CS-don't-care means read-write operation for NAND device to reside
> on the same memory bus as other Flash or SRAM devices. Other devices on 
> the 
> memory bus can then be accessed while the NAND Flash is busy with internal 
> 
> operations. This capability is very important for designs that require 
> multiple
> NAND Flash devices on the same bus.

Yes, we know what CS-dont-care mean, what we want to know is whether
your chip supports that or not. And if it supports it, I don't
understand why you have a problem when asserting/de-asserting on each
->exec_op() call.

> 
> > 
> > Is this behavior publicly documented?
> >   
> 
> CS# pin goes High enter standby mode to reduce power consumption,
> i.e,. standby mode w/ CS# keep High, standby current: 10 uA (Typ for 3.3V 
> NAND)
>         otherwise, current is more than 1 mA.
> i.e,. page read current, 25 mA (Typ for 3.3V NAND)

That's not what we were looking for. We want to know what happens when
the CS line is de-asserted in the middle of a NAND operation (like read
param page). I'd expect the NAND to retain its state so that the
operation can be resumed when the CS line is asserted again. If that's
not the case that means the NAND is not really CS-dont-care compliant.

>  
> 
> > Is this LPM mode always activated?
> >   
> > > i.e,. 
> > > 
> > > 1) In nand_onfi_detect() to call nand_exec_op() twice by 
> > > nand_read_param_page_op() and annd_read_data_op()
> > > 
> > > 2) In nand_write_page_xxx to call nand_exec_op() many times by
> > > nand_prog_page_begin_op(), nand_write_data_op() and 
> > > nand_prog_page_end_op().
> > > 
> > > 
> > > Should we consider to add a CS line controller in struct   
> nand_controller
> > > i.e,.
> > > 
> > > struct nand_controller {
> > >          struct mutex lock;
> > >          const struct nand_controller_ops *ops;
> > > +          void (*select_chip)(struct nand_chip *chip, int cs);
> > > };
> > > 
> > > to replace legacy.select_chip() ?
> > >   
> > 
> > No, if really needed, we could add a "macro op done" flag in the nand
> > operation structure.
> >   
> 
> Is this "macron op done" flag good for multiple NAND devices on
> the same bus ?

It's completely orthogonal to the multi-chip feature, so yes, it should
work just fine.

> 
> Any other way to control CS# pin? if user application is really
> care of power consumption, i.e,. loT.

No, the user is not in control of the CS pin, only the driver can do
that.

Can you please point us to the datasheet of the NAND you're testing, or
something close enough?

Thanks,

Boris

On Tue, 18 Jun 2019 08:14:36 +0200
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> > > > > > 
> > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > low-power standby mode if driver don't use "legacy.select_chip()"     
> > ?   
> > > > > 
> > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip()     
> > optional  
> > > > > when ->exec_op() is implemented") which states:
> > > > > 
> > > > >         "When [->select_chip() is] not implemented, the core is     
> > assuming  
> > > > >    the CS line is automatically asserted/deasserted by the driver     
> > > > >    ->exec_op() implementation."     
> > > > > 
> > > > > Of course, the above is right only when the controller driver     
> > supports  
> > > > > the ->exec_op() interface.     
> > > > 
> > > > Currently, it seems that we will get the incorrect data and error
> > > > operation due to CS in error toggling if CS line is controlled in     
> > > > ->exec_op().     

Oh, and please provide the modifications you added on top of this patch.
Right now we're speculating on what you've done which is definitely not
an efficient way to debug this sort of issues.

Hi Boris,

> 
> Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller
> 
> On Tue, 18 Jun 2019 08:14:36 +0200
> Boris Brezillon <boris.brezillon@collabora.com> wrote:
> 
> > > > > > > 
> > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > low-power standby mode if driver don't use 
"legacy.select_chip()" 
> > > ? 
> > > > > > 
> > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip()  
> > > optional 
> > > > > > when ->exec_op() is implemented") which states:
> > > > > > 
> > > > > >         "When [->select_chip() is] not implemented, the core 
is 
> > > assuming 
> > > > > >    the CS line is automatically asserted/deasserted by the 
driver 
> > > > > >    ->exec_op() implementation." 
> > > > > > 
> > > > > > Of course, the above is right only when the controller driver  
 
> > > supports 
> > > > > > the ->exec_op() interface. 
> > > > > 
> > > > > Currently, it seems that we will get the incorrect data and 
error
> > > > > operation due to CS in error toggling if CS line is controlled 
in 
> > > > > ->exec_op(). 
> 
> Oh, and please provide the modifications you added on top of this patch.
> Right now we're speculating on what you've done which is definitely not
> an efficient way to debug this sort of issues.

The patch is to add in beginning of ->exec_op() to control CS# low and 
before return from ->exec_op() to control CS# High.
i.e,.
static in mxic_nand_exec_op( )
{
 cs_to_low();



 cs_to_high();
 return;
}

But for nand_onfi_detect(), 
it calls nand_read_param_page_op() and then nand_read_data_op().
mxic_nand_exec_op() be called twice for nand_onfi_detect() and
driver will get incorrect ONFI parameter table data from 
nand_read_data_op().

thanks & best regards,
Mason










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============================================================================

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Hi Mason,

masonccyang@mxic.com.tw wrote on Wed, 19 Jun 2019 16:04:43 +0800:

> Hi Boris,
> 
> > 
> > Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller
> > 
> > On Tue, 18 Jun 2019 08:14:36 +0200
> > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> >   
> > > > > > > > 
> > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > low-power standby mode if driver don't use   
> "legacy.select_chip()" 
> > > > ?   
> > > > > > > 
> > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip()    
> > > > optional   
> > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > 
> > > > > > >         "When [->select_chip() is] not implemented, the core   
> is 
> > > > assuming   
> > > > > > >    the CS line is automatically asserted/deasserted by the   
> driver 
> > > > > > >    ->exec_op() implementation."   
> > > > > > > 
> > > > > > > Of course, the above is right only when the controller driver    
>  
> > > > supports   
> > > > > > > the ->exec_op() interface.   
> > > > > > 
> > > > > > Currently, it seems that we will get the incorrect data and   
> error
> > > > > > operation due to CS in error toggling if CS line is controlled   
> in 
> > > > > > ->exec_op().   
> > 
> > Oh, and please provide the modifications you added on top of this patch.
> > Right now we're speculating on what you've done which is definitely not
> > an efficient way to debug this sort of issues.  
> 

We really need to see the datasheet of the NAND chip which has a
problem and how this LPM mode is advertized to understand what the
chip expects and eventually how to work-around it.

> The patch is to add in beginning of ->exec_op() to control CS# low and 
> before return from ->exec_op() to control CS# High.
> i.e,.
> static in mxic_nand_exec_op( )
> {
>  cs_to_low();
> 
> 
> 
>  cs_to_high();
>  return;
> }
> 
> But for nand_onfi_detect(), 
> it calls nand_read_param_page_op() and then nand_read_data_op().
> mxic_nand_exec_op() be called twice for nand_onfi_detect()

Yes, this is expected and usually chips don't care.

> and
> driver will get incorrect ONFI parameter table data from 
> nand_read_data_op().
> 

Thanks,
Miquèl

On Wed, 19 Jun 2019 16:04:43 +0800
masonccyang@mxic.com.tw wrote:

> Hi Boris,
> 
> > 
> > Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller
> > 
> > On Tue, 18 Jun 2019 08:14:36 +0200
> > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> >   
> > > > > > > > 
> > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > low-power standby mode if driver don't use   
> "legacy.select_chip()" 
> > > > ?   
> > > > > > > 
> > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip()    
> > > > optional   
> > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > 
> > > > > > >         "When [->select_chip() is] not implemented, the core   
> is 
> > > > assuming   
> > > > > > >    the CS line is automatically asserted/deasserted by the   
> driver 
> > > > > > >    ->exec_op() implementation."   
> > > > > > > 
> > > > > > > Of course, the above is right only when the controller driver    
>  
> > > > supports   
> > > > > > > the ->exec_op() interface.   
> > > > > > 
> > > > > > Currently, it seems that we will get the incorrect data and   
> error
> > > > > > operation due to CS in error toggling if CS line is controlled   
> in 
> > > > > > ->exec_op().   
> > 
> > Oh, and please provide the modifications you added on top of this patch.
> > Right now we're speculating on what you've done which is definitely not
> > an efficient way to debug this sort of issues.  
> 
> The patch is to add in beginning of ->exec_op() to control CS# low and 
> before return from ->exec_op() to control CS# High.
> i.e,.
> static in mxic_nand_exec_op( )
> {
>  cs_to_low();
> 
> 
> 
>  cs_to_high();
>  return;
> }
> 
> But for nand_onfi_detect(), 
> it calls nand_read_param_page_op() and then nand_read_data_op().
> mxic_nand_exec_op() be called twice for nand_onfi_detect() and
> driver will get incorrect ONFI parameter table data from 
> nand_read_data_op().

And I think it's valid to release the CE pin between
read_param_page_op() (CMD(0xEC)+ADDR(0x0)) and read_data_op() (data
cycles) if your chip is CE-dont-care compliant. So, either you have a
problem with your controller driver (CS-related timings are incorrect)
or your chip is not CE-dont-care compliant.

Hi Miquel,

> > > 
> > > Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND 
controller
> > > 
> > > On Tue, 18 Jun 2019 08:14:36 +0200
> > > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> > > 
> > > > > > > > > 
> > > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > > low-power standby mode if driver don't use 
> > "legacy.select_chip()" 
> > > > > ? 
> > > > > > > > 
> > > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make 
->select_chip() 
> > > > > optional 
> > > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > > 
> > > > > > > >         "When [->select_chip() is] not implemented, the 
core 
> > is 
> > > > > assuming 
> > > > > > > >    the CS line is automatically asserted/deasserted by the 
 
> > driver 
> > > > > > > >    ->exec_op() implementation." 
> > > > > > > > 
> > > > > > > > Of course, the above is right only when the controller 
driver 
> > 
> > > > > supports 
> > > > > > > > the ->exec_op() interface. 
> > > > > > > 
> > > > > > > Currently, it seems that we will get the incorrect data and  

> > error
> > > > > > > operation due to CS in error toggling if CS line is 
controlled 
> > in 
> > > > > > > ->exec_op(). 
> > > 
> > > Oh, and please provide the modifications you added on top of this 
patch.
> > > Right now we're speculating on what you've done which is definitely 
not
> > > an efficient way to debug this sort of issues. 
> > 
> 
> We really need to see the datasheet of the NAND chip which has a
> problem and how this LPM mode is advertized to understand what the
> chip expects and eventually how to work-around it.

okay, got it and thanks.

> 
> > The patch is to add in beginning of ->exec_op() to control CS# low and 

> > before return from ->exec_op() to control CS# High.
> > i.e,.
> > static in mxic_nand_exec_op( )
> > {
> >  cs_to_low();
> > 
> > 
> > 
> >  cs_to_high();
> >  return;
> > }
> > 
> > But for nand_onfi_detect(), 
> > it calls nand_read_param_page_op() and then nand_read_data_op().
> > mxic_nand_exec_op() be called twice for nand_onfi_detect()
> 
> Yes, this is expected and usually chips don't care.

got it and I will try to fix it on my NFC driver.

> 
> > and
> > driver will get incorrect ONFI parameter table data from 
> > nand_read_data_op().
> > 
> 
> Thanks,
> Miquèl

best regards,
Mason

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Hi Boris,

> > > 
> > > Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND 
controller
> > > 
> > > On Tue, 18 Jun 2019 08:14:36 +0200
> > > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> > > 
> > > > > > > > > 
> > > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > > low-power standby mode if driver don't use 
> > "legacy.select_chip()" 
> > > > > ? 
> > > > > > > > 
> > > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make 
->select_chip() 
> > > > > optional 
> > > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > > 
> > > > > > > >         "When [->select_chip() is] not implemented, the 
core 
> > is 
> > > > > assuming 
> > > > > > > >    the CS line is automatically asserted/deasserted by the 
 
> > driver 
> > > > > > > >    ->exec_op() implementation." 
> > > > > > > > 
> > > > > > > > Of course, the above is right only when the controller 
driver 
> > 
> > > > > supports 
> > > > > > > > the ->exec_op() interface. 
> > > > > > > 
> > > > > > > Currently, it seems that we will get the incorrect data and  

> > error
> > > > > > > operation due to CS in error toggling if CS line is 
controlled 
> > in 
> > > > > > > ->exec_op(). 
> > > 
> > > Oh, and please provide the modifications you added on top of this 
patch.
> > > Right now we're speculating on what you've done which is definitely 
not
> > > an efficient way to debug this sort of issues. 
> > 
> > The patch is to add in beginning of ->exec_op() to control CS# low and 

> > before return from ->exec_op() to control CS# High.
> > i.e,.
> > static in mxic_nand_exec_op( )
> > {
> >  cs_to_low();
> > 
> > 
> > 
> >  cs_to_high();
> >  return;
> > }
> > 
> > But for nand_onfi_detect(), 
> > it calls nand_read_param_page_op() and then nand_read_data_op().
> > mxic_nand_exec_op() be called twice for nand_onfi_detect() and
> > driver will get incorrect ONFI parameter table data from 
> > nand_read_data_op().
> 
> And I think it's valid to release the CE pin between
> read_param_page_op() (CMD(0xEC)+ADDR(0x0)) and read_data_op() (data
> cycles) if your chip is CE-dont-care compliant. So, either you have a
> problem with your controller driver (CS-related timings are incorrect)
> or your chip is not CE-dont-care compliant.

Understood, I will try to fix it on my NFC driver.

And I think CS# pin goes to high is much important for power consumption.

thanks & best regards,
Mason





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============================================================================

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On Wed, 19 Jun 2019 16:55:52 +0800
masonccyang@mxic.com.tw wrote:

> Hi Boris,
> 
> > > > 
> > > > Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND   
> controller
> > > > 
> > > > On Tue, 18 Jun 2019 08:14:36 +0200
> > > > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> > > >   
> > > > > > > > > > 
> > > > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > > > low-power standby mode if driver don't use   
> > > "legacy.select_chip()"   
> > > > > > ?   
> > > > > > > > > 
> > > > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make   
> ->select_chip()   
> > > > > > optional   
> > > > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > > > 
> > > > > > > > >         "When [->select_chip() is] not implemented, the   
> core 
> > > is   
> > > > > > assuming   
> > > > > > > > >    the CS line is automatically asserted/deasserted by the   
>  
> > > driver   
> > > > > > > > >    ->exec_op() implementation."   
> > > > > > > > > 
> > > > > > > > > Of course, the above is right only when the controller   
> driver 
> > >   
> > > > > > supports   
> > > > > > > > > the ->exec_op() interface.   
> > > > > > > > 
> > > > > > > > Currently, it seems that we will get the incorrect data and    
> 
> > > error  
> > > > > > > > operation due to CS in error toggling if CS line is   
> controlled 
> > > in   
> > > > > > > > ->exec_op().   
> > > > 
> > > > Oh, and please provide the modifications you added on top of this   
> patch.
> > > > Right now we're speculating on what you've done which is definitely   
> not
> > > > an efficient way to debug this sort of issues.   
> > > 
> > > The patch is to add in beginning of ->exec_op() to control CS# low and   
> 
> > > before return from ->exec_op() to control CS# High.
> > > i.e,.
> > > static in mxic_nand_exec_op( )
> > > {
> > >  cs_to_low();
> > > 
> > > 
> > > 
> > >  cs_to_high();
> > >  return;
> > > }
> > > 
> > > But for nand_onfi_detect(), 
> > > it calls nand_read_param_page_op() and then nand_read_data_op().
> > > mxic_nand_exec_op() be called twice for nand_onfi_detect() and
> > > driver will get incorrect ONFI parameter table data from 
> > > nand_read_data_op().  
> > 
> > And I think it's valid to release the CE pin between
> > read_param_page_op() (CMD(0xEC)+ADDR(0x0)) and read_data_op() (data
> > cycles) if your chip is CE-dont-care compliant. So, either you have a
> > problem with your controller driver (CS-related timings are incorrect)
> > or your chip is not CE-dont-care compliant.  
> 
> Understood, I will try to fix it on my NFC driver.

Before you do that, can you please try to understand where the problem
comes from and explain it to us? Hacking the NFC driver is only
meaningful if the problem is on the NFC side. If your NAND chip does
not support when the CS pin goes high between read_param_page_op() and
read_data_op() the problem should be fixed in the core.

Hi Boris,


> > > > > Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND 
> > controller
> > > > > 
> > > > > On Tue, 18 Jun 2019 08:14:36 +0200
> > > > > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > > > > low-power standby mode if driver don't use 
> > > > "legacy.select_chip()" 
> > > > > > > ? 
> > > > > > > > > > 
> > > > > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make 
> > ->select_chip() 
> > > > > > > optional 
> > > > > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > > > > 
> > > > > > > > > >         "When [->select_chip() is] not implemented, 
the 
> > core 
> > > > is 
> > > > > > > assuming 
> > > > > > > > > >    the CS line is automatically asserted/deasserted by 
the 
> > 
> > > > driver 
> > > > > > > > > >    ->exec_op() implementation." 
> > > > > > > > > > 
> > > > > > > > > > Of course, the above is right only when the controller 
 
> > driver 
> > > > 
> > > > > > > supports 
> > > > > > > > > > the ->exec_op() interface. 
> > > > > > > > > 
> > > > > > > > > Currently, it seems that we will get the incorrect data 
and 
> > 
> > > > error 
> > > > > > > > > operation due to CS in error toggling if CS line is 
> > controlled 
> > > > in 
> > > > > > > > > ->exec_op(). 
> > > > > 
> > > > > Oh, and please provide the modifications you added on top of 
this 
> > patch.
> > > > > Right now we're speculating on what you've done which is 
definitely 
> > not
> > > > > an efficient way to debug this sort of issues. 
> > > > 
> > > > The patch is to add in beginning of ->exec_op() to control CS# low 
and 
> > 
> > > > before return from ->exec_op() to control CS# High.
> > > > i.e,.
> > > > static in mxic_nand_exec_op( )
> > > > {
> > > >  cs_to_low();
> > > > 
> > > > 
> > > > 
> > > >  cs_to_high();
> > > >  return;
> > > > }
> > > > 
> > > > But for nand_onfi_detect(), 
> > > > it calls nand_read_param_page_op() and then nand_read_data_op().
> > > > mxic_nand_exec_op() be called twice for nand_onfi_detect() and
> > > > driver will get incorrect ONFI parameter table data from 
> > > > nand_read_data_op(). 
> > > 
> > > And I think it's valid to release the CE pin between
> > > read_param_page_op() (CMD(0xEC)+ADDR(0x0)) and read_data_op() (data
> > > cycles) if your chip is CE-dont-care compliant. So, either you have 
a
> > > problem with your controller driver (CS-related timings are 
incorrect)
> > > or your chip is not CE-dont-care compliant. 
> > 
> > Understood, I will try to fix it on my NFC driver.
> 
> Before you do that, can you please try to understand where the problem
> comes from and explain it to us? Hacking the NFC driver is only
> meaningful if the problem is on the NFC side. If your NAND chip does
> not support when the CS pin goes high between read_param_page_op() and
> read_data_op() the problem should be fixed in the core.

I think I have fixed the problem and the root cause is the our NFC's TX 
FIFO counter 
do a unnecessary reset in CS control function. Our NFC implement 
read-write 
buffer transfer to send command, address and data.
A unnecessary reset to TX FIFO will send a command byte out first and this 
extra
command will make something wrong to next operation.

For now, doing CS# control in ->exec_op() is OK to me.

thanks & best regards,
Mason



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============================================================================

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Hi Miquel, 


> > > > > > > > > How to make all #CS keep high for NAND to enter 
> > > > > > > > > low-power standby mode if driver don't use 
> > "legacy.select_chip()" 
> > > > > ? 
> > > > > > > > 
> > > > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make 
->select_chip() 
> > > > > optional 
> > > > > > > > when ->exec_op() is implemented") which states:
> > > > > > > > 
> > > > > > > >         "When [->select_chip() is] not implemented, the 
core 
> > is 
> > > > > assuming 
> > > > > > > >    the CS line is automatically asserted/deasserted by the 
 
> > driver 
> > > > > > > >    ->exec_op() implementation." 
> > > > > > > > 
> > > > > > > > Of course, the above is right only when the controller 
driver 
> > 
> > > > > supports 
> > > > > > > > the ->exec_op() interface. 
> > > > > > > 
> > > > > > > Currently, it seems that we will get the incorrect data and  

> > error
> > > > > > > operation due to CS in error toggling if CS line is 
controlled 
> > in 
> > > > > > > ->exec_op(). 
> > > 
> > > Oh, and please provide the modifications you added on top of this 
patch.
> > > Right now we're speculating on what you've done which is definitely 
not
> > > an efficient way to debug this sort of issues. 
> > 
> 
> We really need to see the datasheet of the NAND chip which has a
> problem and how this LPM mode is advertized to understand what the
> chip expects and eventually how to work-around it.
> 
> > The patch is to add in beginning of ->exec_op() to control CS# low and 

> > before return from ->exec_op() to control CS# High.
> > i.e,.
> > static in mxic_nand_exec_op( )
> > {
> >  cs_to_low();
> > 
> > 
> > 
> >  cs_to_high();
> >  return;
> > }
> > 
> > But for nand_onfi_detect(), 
> > it calls nand_read_param_page_op() and then nand_read_data_op().
> > mxic_nand_exec_op() be called twice for nand_onfi_detect()
> 
> Yes, this is expected and usually chips don't care.

As I replied to Boris's email previously.
I think I have fixed the problem and the root cause is the our NFC's TX 
FIFO 
counter do a unnecessary reset in CS control function.
currently, doing CS# control in ->exec_op() is OK to me.

In addition, by Jones's comments about MFD, 
I will re-submit this raw NAND ctlr driver instead of MFD and raw-nand. 
----------------------------------------------------------------------->
MFD is for registering child devices of chips which offer 
genuine cross-subsystem functionality. 

It is not designed for mode selecting, or as a place to shove shared code 
just because a better location doesn't appear to exist. 
------------------------------------------------------------------------<

thanks & best regards,
Mason






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