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authorBrian Norris <computersforpeace@gmail.com>2011-06-23 16:45:24 -0700
committerArtem Bityutskiy <artem.bityutskiy@intel.com>2011-09-11 15:02:14 +0300
commit041e4575f03400e045f00a823fcbbbb337de8409 (patch)
tree3fa062bee497a7ff13d908bf2204de4ec04888da /drivers
parentd6137badeff1ef64b4e0092ec249ebdeaeb3ff37 (diff)
mtd: nand: handle ECC errors in OOB
While the standard NAND OOB functions do not do ECC on the spare area, it is possible for a driver to supply its own OOB ECC functions (e.g., HW ECC). nand_do_read_oob should act like nand_do_read_ops in checking the ECC stats and returning -EBADMSG or -EUCLEAN on uncorrectable errors or correctable bitflips, respectively. These error codes could be used in flash-based BBT code or in YAFFS, for example. Doing this, however, messes with the behavior of mtd_do_readoob. Now, mtd_do_readoob should check whether we had -EUCLEAN or -EBADMSG errors and discard those as "non-fatal" so that the ioctls can still succeed with (possibly uncorrected) data. Signed-off-by: Brian Norris <computersforpeace@gmail.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/mtd/mtdchar.c15
-rw-r--r--drivers/mtd/nand/nand_base.c9
2 files changed, 23 insertions, 1 deletions
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index c60067b1f07a..d5924635ead5 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -473,6 +473,21 @@ static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,
ret = -EFAULT;
kfree(ops.oobbuf);
+
+ /*
+ * NAND returns -EBADMSG on ECC errors, but it returns the OOB
+ * data. For our userspace tools it is important to dump areas
+ * with ECC errors!
+ * For kernel internal usage it also might return -EUCLEAN
+ * to signal the caller that a bitflip has occured and has
+ * been corrected by the ECC algorithm.
+ *
+ * Note: most NAND ECC algorithms do not calculate ECC
+ * for the OOB area.
+ */
+ if (ret == -EUCLEAN || ret == -EBADMSG)
+ return 0;
+
return ret;
}
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 237d7daa189c..5418d27122c4 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1750,6 +1750,7 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
{
int page, realpage, chipnr, sndcmd = 1;
struct nand_chip *chip = mtd->priv;
+ struct mtd_ecc_stats stats;
int blkcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;
int readlen = ops->ooblen;
int len;
@@ -1758,6 +1759,8 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
DEBUG(MTD_DEBUG_LEVEL3, "%s: from = 0x%08Lx, len = %i\n",
__func__, (unsigned long long)from, readlen);
+ stats = mtd->ecc_stats;
+
if (ops->mode == MTD_OOB_AUTO)
len = chip->ecc.layout->oobavail;
else
@@ -1828,7 +1831,11 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
}
ops->oobretlen = ops->ooblen;
- return 0;
+
+ if (mtd->ecc_stats.failed - stats.failed)
+ return -EBADMSG;
+
+ return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
}
/**