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

[Simon Glass <sjg@chromium.org>]

Hi Gerlando,

On Tue, Apr 3, 2012 at 8:14 AM, Gerlando Falauto
<gerlando.falauto@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@keymile.com>
> Cc: Valentin Longchamp <valentin.longchamp@keymile.com>
> Cc: Holger Brunck <holger.brunck@keymile.com>

Acked-by: Simon Glass <sjg@chromium.org>

> ---
> ?common/cmd_sf.c | ? 15 ++++++++++++++-
> ?1 files changed, 14 insertions(+), 1 deletions(-)
>
> diff --git a/common/cmd_sf.c b/common/cmd_sf.c
> index d97d4a5..0666f52 100644
> --- a/common/cmd_sf.c
> +++ b/common/cmd_sf.c
> @@ -134,8 +134,10 @@ 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 meningful (len) */
> ? ? ? ?if (memcmp(cmp_buf, buf, len) == 0) {
> ? ? ? ? ? ? ? ?debug("Skip region %x size %zx: no change\n",
> ? ? ? ? ? ? ? ? ? ? ? ?offset, len);
> @@ -145,6 +147,17 @@ 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";
> + ? ? ? /* If it's a partial sector, preserve the existing part */
> + ? ? ? if (len != flash->sector_size) {
> + ? ? ? ? ? ? ? /* Overwrite the first part of the sector with input data */
> + ? ? ? ? ? ? ? memcpy(cmp_buf, buf, len);
> + ? ? ? ? ? ? ? /* Rewrite the whole sector with original data at the end */
> + ? ? ? ? ? ? ? if (spi_flash_write(flash, offset, flash->sector_size,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? cmp_buf))
> + ? ? ? ? ? ? ? ? ? ? ? return "write";
> + ? ? ? ? ? ? ? return NULL;

If you wrote just the last part of the sector here then you could
perhaps avoid the memcpy() and the return NULL.

> + ? ? ? }
> + ? ? ? /* Rewrite the whole block from the source */
> ? ? ? ?if (spi_flash_write(flash, offset, len, buf))
> ? ? ? ? ? ? ? ?return "write";
> ? ? ? ?return NULL;
> --
> 1.7.1
>

Regards,
Simon