[PATCH 3.13 043/198] mtd: nand: omap: fix BCHx ecc.correct to return detected bit-flips in erased-page

From: Kamal Mostafa
Date: Tue Jul 15 2014 - 18:00:02 EST -stable review patch. If anyone has any objections, please let me know.


From: pekon gupta <pekon@xxxxxx>

commit f306e8c3b667632952f1a4a74ffb910bbc06255f upstream.

fixes: commit 62116e5171e00f85a8d53f76e45b84423c89ff34
mtd: nand: omap2: Support for hardware BCH error correction.

In omap_elm_correct_data(), if bitflip_count in an erased-page is within the
correctable limit (< ecc.strength), then it is not indicated back to the caller

This mis-guides upper layers like MTD and UBIFS layer to assume erased-page as
perfectly clean and use it for writing even if actual bitflip_count was
dangerously high (bitflip_count > mtd->bitflip_threshold).

This patch fixes this above issue, by returning 'stats' to caller
ecc->read_page() under all scenarios.

Reported-by: Brian Norris <computersforpeace@xxxxxxxxx>
Signed-off-by: Pekon Gupta <pekon@xxxxxx>
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
drivers/mtd/nand/omap2.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 2365b5a..b594e61 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -1451,7 +1451,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,

/* Check if any error reported */
if (!is_error_reported)
- return 0;
+ return stat;

/* Decode BCH error using ELM module */
elm_decode_bch_error_page(info->elm_dev, ecc_vec, err_vec);

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