[U-Boot] [PATCH] sf: Make 4K sector support configurable

[Jagan Teki]

On 3 August 2015 at 04:58, Marek Vasut <marex at denx.de> wrote:
> Make the support for 4K subpage I/O on a SPI NOR flash configurable.
> A board which requires the SPI NOR to be accessed in larger 32KiB
> or 64KiB pages can disable the 4K subpage support, but by default,
> the support for 4K subpage I/O is enabled. The functionality of this
> option is the same as CONFIG_MTD_SPI_NOR_USE_4K_SECTORS in Linux.
>
> This is extremely useful in case one uses UBI on a SPI NOR flash.
> UBI needs at least 15k EBs and can not work on a flash which uses
> 4k ones, so disabling the support for 4k subpages lets UBI work on
> such flash.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Jagan Teki <jteki at openedev.com>
> ---
>  drivers/mtd/spi/Kconfig       | 15 +++++++++++++++
>  drivers/mtd/spi/sf_internal.h |  4 ++++
>  2 files changed, 19 insertions(+)
>
> diff --git a/drivers/mtd/spi/Kconfig b/drivers/mtd/spi/Kconfig
> index 8b730ff..3f7433c 100644
> --- a/drivers/mtd/spi/Kconfig
> +++ b/drivers/mtd/spi/Kconfig
> @@ -86,6 +86,21 @@ config SPI_FLASH_WINBOND
>
>  endif
>
> +config SPI_FLASH_USE_4K_SECTORS
> +       bool "Use small 4096 B erase sectors"
> +       depends on SPI_FLASH
> +       default y
> +       help
> +         Many flash memories support erasing small (4096 B) sectors. Depending
> +         on the usage this feature may provide performance gain in comparison
> +         to erasing whole blocks (32/64 KiB).
> +         Changing a small part of the flash's contents is usually faster with
> +         small sectors. On the other hand erasing should be faster when using
> +         64 KiB block instead of 16 × 4 KiB sectors.
> +
> +         Please note that some tools/drivers/filesystems may not work with
> +         4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).
> +
>  config SPI_FLASH_DATAFLASH
>         bool "AT45xxx DataFlash support"
>         depends on SPI_FLASH && DM_SPI_FLASH
> diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
> index 9fb5557..9c95d56 100644
> --- a/drivers/mtd/spi/sf_internal.h
> +++ b/drivers/mtd/spi/sf_internal.h
> @@ -37,7 +37,11 @@ enum spi_read_cmds {
>
>  /* sf param flags */
>  enum {
> +#ifdef CONFIG_SPI_FLASH_USE_4K_SECTORS
>         SECT_4K         = 1 << 0,
> +#else
> +       SECT_4K         = 0 << 0,
> +#endif
>         SECT_32K        = 1 << 1,
>         E_FSR           = 1 << 2,
>         SST_BP          = 1 << 3,
> --
> 2.1.4

Reviewed-by: Jagan Teki <jteki at openedev.com>

thanks!
-- 
Jagan | openedev.