linux-kernel - Re: [PATCH v3 3/3] mtd: spi-nor: Favor the BFPT-parsed set_4byte_addr

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Date:   Thu, 14 Apr 2022 11:21:52 +0200
From:   Michael Walle <michael@...le.cc>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>
Cc:     p.yadav@...com, miquel.raynal@...tlin.com, richard@....at,
        vigneshr@...com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, nicolas.ferre@...rochip.com
Subject: Re: [PATCH v3 3/3] mtd: spi-nor: Favor the BFPT-parsed
 set_4byte_addr_mode method

Am 2022-04-11 14:53, schrieb Tudor Ambarus:
> JESD216 SFDP defines in the BFPT standard methods to enter and exit the
> 4-Byte Address Mode. The flash parameters and settings that are 
> retrieved
> from SFDP have higher precedence than the static initialized ones, 
> because
> they should be more accurate and less error prone than those 
> initialized
> statically. Favor the BFPT-parsed set_4byte_addr_mode method and use 
> the
> generic core methods where possible.
> This patch may introduce regressions in case BFPT contains wrong data. 
> The
> fix is to introduce a post_bfpt() fixup hook and update the wrong BFPT
> data.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> Reviewed-by: Pratyush Yadav <p.yadav@...com>
> ---
> v3: no changes
> 
>  drivers/mtd/spi-nor/core.c      |  7 ++++++-
>  drivers/mtd/spi-nor/macronix.c  | 10 ++++++++--
>  drivers/mtd/spi-nor/micron-st.c |  9 ++++++---
>  3 files changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 4d45cda4f9d3..888516d98884 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2416,6 +2416,8 @@ static void spi_nor_init_fixup_flags(struct 
> spi_nor *nor)
>   */
>  static void spi_nor_late_init_params(struct spi_nor *nor)
>  {
> +	struct spi_nor_flash_parameter *params = nor->params;
> +
>  	if (nor->manufacturer && nor->manufacturer->fixups &&
>  	    nor->manufacturer->fixups->late_init)
>  		nor->manufacturer->fixups->late_init(nor);
> @@ -2423,6 +2425,10 @@ static void spi_nor_late_init_params(struct 
> spi_nor *nor)
>  	if (nor->info->fixups && nor->info->fixups->late_init)
>  		nor->info->fixups->late_init(nor);
> 
> +	/* Default method kept for backward compatibility. */
> +	if (!params->set_4byte_addr_mode)
> +		params->set_4byte_addr_mode = spi_nor_set_4byte_addr_mode_brwr;

Can this be moved past..

> +
>  	spi_nor_init_flags(nor);
>  	spi_nor_init_fixup_flags(nor);

.. these two lines, so it is next to the "set default
locking ops"?

> 
> @@ -2490,7 +2496,6 @@ static void spi_nor_init_default_params(struct
> spi_nor *nor)
>  	struct device_node *np = spi_nor_get_flash_node(nor);
> 
>  	params->quad_enable = spi_nor_sr2_bit1_quad_enable;
> -	params->set_4byte_addr_mode = spi_nor_set_4byte_addr_mode_brwr;
>  	params->otp.org = &info->otp_org;
> 
>  	/* Default to 16-bit Write Status (01h) Command */
> diff --git a/drivers/mtd/spi-nor/macronix.c 
> b/drivers/mtd/spi-nor/macronix.c
> index 85e8655d362c..c267cbcc7f1d 100644
> --- a/drivers/mtd/spi-nor/macronix.c
> +++ b/drivers/mtd/spi-nor/macronix.c
> @@ -105,12 +105,18 @@ static const struct flash_info 
> macronix_nor_parts[] = {
>  static void macronix_nor_default_init(struct spi_nor *nor)
>  {
>  	nor->params->quad_enable = spi_nor_sr1_bit6_quad_enable;
> -	nor->params->set_4byte_addr_mode =
> -		spi_nor_set_4byte_addr_mode_en4b_ex4b;
> +}
> +
> +static void macronix_nor_late_init(struct spi_nor *nor)
> +{
> +	if (!nor->params->set_4byte_addr_mode)
> +		nor->params->set_4byte_addr_mode =
> +			spi_nor_set_4byte_addr_mode_en4b_ex4b;

This is more of a general question. Can we have this in one
line? IMHO this looks awful and since linux nowadays relaxed the
80 chars rule a bit and we have such long names.. I think it makes
sense to allow some lines to be longer than 80 chars.

>  }
> 
>  static const struct spi_nor_fixups macronix_nor_fixups = {
>  	.default_init = macronix_nor_default_init,
> +	.late_init = macronix_nor_late_init,
>  };
> 
>  const struct spi_nor_manufacturer spi_nor_macronix = {
> diff --git a/drivers/mtd/spi-nor/micron-st.c 
> b/drivers/mtd/spi-nor/micron-st.c
> index 2d1cbb1f37c8..9e9b107f2018 100644
> --- a/drivers/mtd/spi-nor/micron-st.c
> +++ b/drivers/mtd/spi-nor/micron-st.c
> @@ -414,14 +414,17 @@ static void micron_st_nor_default_init(struct
> spi_nor *nor)
>  	nor->flags |= SNOR_F_HAS_LOCK;
>  	nor->flags &= ~SNOR_F_HAS_16BIT_SR;
>  	nor->params->quad_enable = NULL;
> -	nor->params->set_4byte_addr_mode =
> -		spi_nor_set_4byte_addr_mode_wren_en4b_ex4b;
>  }
> 
>  static void micron_st_nor_late_init(struct spi_nor *nor)
>  {
> +	struct spi_nor_flash_parameter *params = nor->params;
> +
>  	if (nor->info->mfr_flags & USE_FSR)
> -		nor->params->ready = micron_st_nor_ready;
> +		params->ready = micron_st_nor_ready;
> +	if (!params->set_4byte_addr_mode)
> +		params->set_4byte_addr_mode =
> +			spi_nor_set_4byte_addr_mode_wren_en4b_ex4b;

same here.

-michael