| Message ID | 1308872724-6196-1-git-send-email-computersforpeace@gmail.com |
|---|---|
| State | Accepted |
| Commit | 041e4575f03400e045f00a823fcbbbb337de8409 |
| Headers | show |
On Thu, 2011-06-23 at 16:45 -0700, Brian Norris wrote: > 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> > --- > drivers/mtd/mtdchar.c | 15 +++++++++++++++ > drivers/mtd/nand/nand_base.c | 9 ++++++++- > 2 files changed, 23 insertions(+), 1 deletions(-) Looks good, pushed to l2-mtd-2.6.git, thanks!
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c index 3f92731..8a45525 100644 --- a/drivers/mtd/mtdchar.c +++ b/drivers/mtd/mtdchar.c @@ -472,6 +472,21 @@ 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 a46e9bb..f0ba2da 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -1761,6 +1761,7 @@ 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; @@ -1769,6 +1770,8 @@ 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 @@ -1838,7 +1841,11 @@ 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; } /**
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> --- drivers/mtd/mtdchar.c | 15 +++++++++++++++ drivers/mtd/nand/nand_base.c | 9 ++++++++- 2 files changed, 23 insertions(+), 1 deletions(-)