[PATCH 1/7] mtd: spi-nor: core: Introduce SPI_NOR_PARSE_SFDP

[Heiko Thiery]

Hi Tudor,

Am Fr., 2. Juli 2021 um 16:41 Uhr schrieb Tudor Ambarus
<tudor.ambarus at microchip.com>:
>
> SPI NOR flashes that statically declare one of the
> SPI_NOR_{DUAL, QUAD, OCTAL, OCTAL_DTR}_READ flags, and do not support
> the RDSFDP command, are gratuiously receiving the RDSFDP command,
> in the attempt of parsing the SFDP tables. It is not desirable to issue
> comands that are not supported, so introduce a flag to help on this
> situation.
>
> New flash additions that support the SFDP standard should be declared
> using SPI_NOR_PARSE_SFDP. Support that can be discovered when parsing
> SFDP should not be duplicated by explicit flags at flash declaration.
> All the flash parameters will be discovered when parsing SFDP.
> Sometimes manufacturers wrongly define some fields in the SFDP tables.
> If that's the case, SFDP data can be ammended with the fixups() hooks.
> It is not common, but if the SFDP tables are entirely wrong, and it
> does not worth the hassle to tweak the SFDP parameters by using the
> fixups hooks, or if the flash does not define the SFDP tables at all,
> then statically init the flash with the SPI_NOR_SKIP_SFDP flag and
> specify the reset of flash capabilities with the flash info flags.
>
> With time, we want to convert all flashes to SPI_NOR_PARSE_SFDP and
> stop triggering the SFDP parsing with the
> SPI_NOR_{DUAL, QUAD, OCTAL*}_READ flags. Getting rid of the
> SPI_NOR_{OCTAL, OCTAL_DTR}_READ trigger is easy achievable, the reset
> are a long term goal.
>
> Signed-off-by: Tudor Ambarus <tudor.ambarus at microchip.com>

Reviewed-by: Heiko Thiery <heiko.thiery at gmail.com>

> ---
>  drivers/mtd/spi-nor/core.c | 3 ++-
>  drivers/mtd/spi-nor/core.h | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index cc08bd707378..3d9f3698fb7b 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2726,7 +2726,8 @@ static int spi_nor_init_params(struct spi_nor *nor)
>
>         spi_nor_manufacturer_init_params(nor);
>
> -       if ((nor->info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
> +       if ((nor->info->flags & (SPI_NOR_PARSE_SFDP |
> +                                SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
>                                  SPI_NOR_OCTAL_READ | SPI_NOR_OCTAL_DTR_READ)) &&
>             !(nor->info->flags & SPI_NOR_SKIP_SFDP))
>                 spi_nor_sfdp_init_params(nor);
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 3348e1dd1445..55fceb0ec894 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -382,6 +382,10 @@ struct flash_info {
>                                          * protection bits. Usually these will
>                                          * power-up in a write-protected state.
>                                          */
> +#define SPI_NOR_PARSE_SFDP     BIT(23) /*
> +                                        * Flash initialized based on the SFDP
> +                                        * tables.
> +                                        */
>
>         const struct spi_nor_otp_organization otp_org;
>

Thank you

--
Heiko