linux-kernel - Re: [RESEND PATCH v3 05/20] mtd: spi-nor: Add default

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Date:   Tue, 27 Aug 2019 11:18:29 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     <Tudor.Ambarus@...rochip.com>, <boris.brezillon@...labora.com>,
        <marek.vasut@...il.com>, <miquel.raynal@...tlin.com>,
        <richard@....at>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v3 05/20] mtd: spi-nor: Add default_init() hook to
 tweak flash parameters



On 26/08/19 5:38 PM, 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 parameters init based on 'flash_info' struct:
> 	spi_nor_info_init_params()
> 
> which can be overwritten by:
> 2/ MFR-based manufacturer flash parameters init:
> 	nor->manufacturer->fixups->default_init()
> 
> which can be overwritten by:
> 3/ specific flash_info tweeks done when decisions can not be done just on
>    MFR:
> 	nor->info->fixups->default_init()
> 
> which can be overwritten by:
> 4/ SFDP tables flash parameters init - SFDP knows better:
> 	spi_nor_sfdp_init_params()
> 
> which can be overwritten by:
> 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>
> ---


Reviewed-by: Vignesh Raghavendra <vigneshr@...com>

Regards
Vignesh

> v3: reword description
> 
>  drivers/mtd/spi-nor/spi-nor.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 9dd6cd8cd13c..8fd60e1eebd2 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -154,12 +154,16 @@ 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);
>  	int (*post_bfpt)(struct spi_nor *nor,
>  			 const struct sfdp_parameter_header *bfpt_header,
>  			 const struct sfdp_bfpt *bfpt,
> @@ -4133,6 +4137,17 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
>  	return err;
>  }
>  
> +/**
> + * spi_nor_manufacturer_init_params() - Initialize the flash's parameters and
> + * settings based on ->default_init() hook.
> + * @nor:	pointer to a 'struct spi-nor'.
> + */
> +static void spi_nor_manufacturer_init_params(struct spi_nor *nor)
> +{
> +	if (nor->info->fixups && nor->info->fixups->default_init)
> +		nor->info->fixups->default_init(nor);
> +}
> +
>  static int spi_nor_init_params(struct spi_nor *nor)
>  {
>  	struct spi_nor_flash_parameter *params = &nor->params;
> @@ -4233,6 +4248,8 @@ static int spi_nor_init_params(struct spi_nor *nor)
>  			params->quad_enable = info->quad_enable;
>  	}
>  
> +	spi_nor_manufacturer_init_params(nor);
> +
>  	if ((info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)) &&
>  	    !(info->flags & SPI_NOR_SKIP_SFDP)) {
>  		struct spi_nor_flash_parameter sfdp_params;
> 

-- 
Regards
Vignesh