[U-Boot] [PATCH v3 2/2] cmd_sf: let "sf update" preserve the final part of the last sector

[Jagan Teki]

On Thu, Jul 4, 2013 at 12:03 AM, Gerlando Falauto
<gerlando.falauto at keymile.com> wrote:
> Since "sf update" erases the last block as a whole, but only rewrites
> the meaningful initial part of it, the rest would be left erased,
> potentially erasing meaningful information.
> So, as a safety measure, have it rewrite the original content.
>
> Signed-off-by: Gerlando Falauto <gerlando.falauto at keymile.com>
> Cc: Valentin Longchamp <valentin.longchamp at keymile.com>
> Cc: Holger Brunck <holger.brunck at keymile.com>
> Acked-by: Simon Glass <sjg at chromium.org>
> ---
>  common/cmd_sf.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/common/cmd_sf.c b/common/cmd_sf.c
> index ab35a94..1141dc1 100644
> --- a/common/cmd_sf.c
> +++ b/common/cmd_sf.c
> @@ -152,8 +152,10 @@ static const char *spi_flash_update_block(struct spi_flash *flash, u32 offset,
>  {
>         debug("offset=%#x, sector_size=%#x, len=%#zx\n",
>                 offset, flash->sector_size, len);
> -       if (spi_flash_read(flash, offset, len, cmp_buf))
> +       /* Read the entire sector so to allow for rewriting */
> +       if (spi_flash_read(flash, offset, flash->sector_size, cmp_buf))
>                 return "read";
> +       /* Compare only what is meaningful (len) */
>         if (memcmp(cmp_buf, buf, len) == 0) {
>                 debug("Skip region %x size %zx: no change\n",
>                         offset, len);
> @@ -163,8 +165,16 @@ static const char *spi_flash_update_block(struct spi_flash *flash, u32 offset,
>         /* Erase the entire sector */
>         if (spi_flash_erase(flash, offset, flash->sector_size))
>                 return "erase";
> +       /* Write the initial part of the block from the source */
>         if (spi_flash_write(flash, offset, len, buf))
>                 return "write";

I din't understand why the below write is required again-
As erase ops requires only sector operation and read + write will do
the operations on partial sizes

Can you send the failure case w/o this.

--
Thanks,
Jagan.
> +       /* If it's a partial sector, rewrite the existing part */
> +       if (len != flash->sector_size) {
> +               /* Rewrite the original data to the end of the sector */
> +               if (spi_flash_write(flash, offset + len,
> +                       flash->sector_size - len, &cmp_buf[len]))
> +                       return "write";
> +       }
>         return NULL;
>  }
>
> --
> 1.8.0.1
>