linux-kernel - Re: [PATCH 1/7] mtd: spi-nor: Add default_init() hook to tweak flash parameters

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Date:   Thu, 1 Aug 2019 08:24:29 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     <Tudor.Ambarus@...rochip.com>
Cc:     <marek.vasut@...il.com>, <vigneshr@...com>, <dwmw2@...radead.org>,
        <computersforpeace@...il.com>, <miquel.raynal@...tlin.com>,
        <richard@....at>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/7] mtd: spi-nor: Add default_init() hook to tweak
 flash parameters

On Wed, 31 Jul 2019 09:03:27 +0000
<Tudor.Ambarus@...rochip.com> wrote:

> From: Tudor Ambarus <tudor.ambarus@...rochip.com>
> 
> As of now, the flash parameters initialization logic is as following:
> 
> a/ default flash parameters init in spi_nor_init_params()
> b/ manufacturer specific flash parameters updates, split across entire
>    spi-nor core code
> c/ flash parameters updates based on SFDP tables
> d/ post BFPT flash parameter updates
> 
> In the quest of removing the manufacturer specific code from the spi-nor
> core, we want to impose a timeline/priority on how the flash parameters
> are updated. The following sequence of calls is pursued:
> 
> 1/ spi-nor core legacy flash parameters init:
> 	spi_nor_default_init_params()
> 
> 2/ MFR-based manufacturer flash parameters init:
> 	nor->manufacturer->fixups->default_init()
> 
> 3/ specific flash_info tweeks done when decisions can not be done just on
>    MFR:
> 	nor->info->fixups->default_init()
> 
> 4/ SFDP tables flash parameters init - SFDP knows better:
> 	spi_nor_sfdp_init_params()
> 
> 5/ post SFDP tables flash parameters updates - in case manufacturers get
>    the serial flash tables wrong or incomplete.
> 	nor->info->fixups->post_sfdp()
>    The later can be extended to nor->manufacturer->fixups->post_sfdp() if
>    needed.
> 
> This patch opens doors for steps 2/ and 3/.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>

> ---
>  drivers/mtd/spi-nor/spi-nor.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 28a64dbdaea9..ac00f90ebaa9 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -219,12 +219,17 @@ struct sfdp_bfpt {
>  
>  /**
>   * struct spi_nor_fixups - SPI NOR fixup hooks
> + * @default_init: called after default flash parameters init. Used to tweak
> + *                flash parameters when information provided by the flash_info
> + *                table is incomplete or wrong.
>   * @post_bfpt: called after the BFPT table has been parsed
>   *
>   * Those hooks can be used to tweak the SPI NOR configuration when the SFDP
>   * table is broken or not available.
>   */
>  struct spi_nor_fixups {
> +	void (*default_init)(struct spi_nor *nor,
> +			     struct spi_nor_flash_parameter *params);
>  	int (*post_bfpt)(struct spi_nor *nor,
>  			 const struct sfdp_parameter_header *bfpt_header,
>  			 const struct sfdp_bfpt *bfpt,
> @@ -4267,6 +4272,14 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
>  	return err;
>  }
>  
> +static void
> +spi_nor_manufacturer_init_params(struct spi_nor *nor,
> +				 struct spi_nor_flash_parameter *params)
> +{
> +	if (nor->info->fixups && nor->info->fixups->default_init)
> +		return nor->info->fixups->default_init(nor, params);
> +}
> +
>  static int spi_nor_init_params(struct spi_nor *nor,
>  			       struct spi_nor_flash_parameter *params)
>  {
> @@ -4370,6 +4383,8 @@ static int spi_nor_init_params(struct spi_nor *nor,
>  			params->quad_enable = info->quad_enable;
>  	}
>  
> +	spi_nor_manufacturer_init_params(nor, params);
> +
>  	if ((info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)) &&
>  	    !(info->flags & SPI_NOR_SKIP_SFDP)) {
>  		struct spi_nor_flash_parameter sfdp_params;