[U-Boot] [PATCH v2 2/2] cmd_sf: "sf update" preserve the final part of the last sector

Gerlando Falauto
2013-06-28T07:43:53Z

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 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/common/cmd_sf.c b/common/cmd_sf.c
index ab35a94..fb87d24 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 meningful (len) */
if (memcmp(cmp_buf, buf, len) == 0) {
debug("Skip region %x size %zx: no change\n",
offset, len);
@@ -163,6 +165,17 @@ 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;
+ }
+ /* Rewrite the whole block from the source */
if (spi_flash_write(flash, offset, len, buf))
return "write";
return NULL;
--
1.7.10.1