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authorAnatolij Gustschin <agust@denx.de>2010-12-16 17:42:19 -0500
committerDavid Woodhouse <David.Woodhouse@intel.com>2011-01-06 10:36:00 -0500
commita121f643993474548fe98144514c50dd4f3dbe76 (patch)
tree184d54ebdbd62977ed4d672058293638fe2e0b2a /drivers
parent7fa33ac0a7e24a1b8bd71be5c47a17423c62fbda (diff)
UBI: use mtd->writebufsize to set minimal I/O unit size
Previously we used mtd->writesize field to set UBI's minimal I/O unit size. This sometimes caused UBIFS recovery issues when mounting an uncleanly unmounted UBIFS partition on NOR flash since mtd->writesize is 1 byte for NOR flash. The MTD CFI driver however often performs writing multiple bytes in one programming operation using the chip's write buffer. We have to use the size of this write buffer as a minimal I/O unit size for UBI on NOR flash to fix the observed UBIFS recovery issues. Signed-off-by: Anatolij Gustschin <agust@denx.de> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/mtd/ubi/build.c28
1 files changed, 27 insertions, 1 deletions
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 5ebe280225d6..f49e49dc5928 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -672,7 +672,33 @@ static int io_init(struct ubi_device *ubi)
672 ubi->nor_flash = 1; 672 ubi->nor_flash = 1;
673 } 673 }
674 674
675 ubi->min_io_size = ubi->mtd->writesize; 675 /*
676 * Set UBI min. I/O size (@ubi->min_io_size). We use @mtd->writebufsize
677 * for these purposes, not @mtd->writesize. At the moment this does not
678 * matter for NAND, because currently @mtd->writebufsize is equivalent to
679 * @mtd->writesize for all NANDs. However, some CFI NOR flashes may
680 * have @mtd->writebufsize which is multiple of @mtd->writesize.
681 *
682 * The reason we use @mtd->writebufsize for @ubi->min_io_size is that
683 * UBI and UBIFS recovery algorithms rely on the fact that if there was
684 * an unclean power cut, then we can find offset of the last corrupted
685 * node, align the offset to @ubi->min_io_size, read the rest of the
686 * eraseblock starting from this offset, and check whether there are
687 * only 0xFF bytes. If yes, then we are probably dealing with a
688 * corruption caused by a power cut, if not, then this is probably some
689 * severe corruption.
690 *
691 * Thus, we have to use the maximum write unit size of the flash, which
692 * is @mtd->writebufsize, because @mtd->writesize is the minimum write
693 * size, not the maximum.
694 */
695 if (ubi->mtd->type == MTD_NANDFLASH)
696 ubi_assert(ubi->mtd->writebufsize == ubi->mtd->writesize);
697 else if (ubi->mtd->type == MTD_NORFLASH)
698 ubi_assert(ubi->mtd->writebufsize % ubi->mtd->writesize == 0);
699
700 ubi->min_io_size = ubi->mtd->writebufsize;
701
676 ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft; 702 ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;
677 703
678 /* 704 /*