Message ID | 1292539339-25111-2-git-send-email-agust@denx.de |
---|---|
State | New, archived |
Headers | show |
On Thu, 2010-12-16 at 23:42 +0100, Anatolij Gustschin wrote: > This field will be used to indicate the write buffer size > of the MTD device. UBI will set it's minimal I/O unit size > (min_io_size) to the indicated write buffer size. By this > change we intend to fix failed recovery of UBIFS partitions > we currently observe on NOR flash when mounting the partition > after unclean unmount. > > Currently the min_io_size is set to mtd->writesize (which is 1 > byte for NOR flash). But flash programming is often done from > prepared write buffer containing multiple bytes and is performed > in one programming operation which could be interrupted by a power > cut or a system reset causing corrupted (partially written) areas > in a flash sector. Knowing the size of potentially corrupted areas > UBIFS scanning and recovery algorithms are able to perform > successful recovery. > > In case of NOR flash minimal I/O size must be equal to the > maximal size of the write buffer used by embedded flash > programming algorithm. In case of NAND flash mtd->writebufsize > should be equivalent to mtd->writesize. > > The subsequent patches will add mtd->writebufsize initialization > where needed. > > Signed-off-by: Anatolij Gustschin <agust@denx.de> I've tweaked your commentary a bit and pushed to l2-mtd-2.6.git, please, check.
On Sun, 19 Dec 2010 19:45:31 +0200 Artem Bityutskiy <dedekind1@gmail.com> wrote: > I've tweaked your commentary a bit and pushed to l2-mtd-2.6.git, please, > check. It is ok. Thanks! Anatolij
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index fe8d77e..3c6db0c 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -144,6 +144,19 @@ struct mtd_info { */ uint32_t writesize; + /* + * Size of the write buffer used by the MTD. + * MTD devices having a write buffer can write multiple writesize + * chunks at a time. E.g. while writing 4 * writesize bytes to a + * device with 2 * writesize bytes buffer the MTD driver can (but + * doesn't have to) do 2 writesize operations, but not 4. + * In case of NAND flash writebufsize should be equivalent to + * writesize. In case of NOR flash writebufsize is the size of the + * write buffer used by the MTD device to program multiple bytes + * at a time (in one programming operation). + */ + uint32_t writebufsize; + uint32_t oobsize; // Amount of OOB data per block (e.g. 16) uint32_t oobavail; // Available OOB bytes per block
This field will be used to indicate the write buffer size of the MTD device. UBI will set it's minimal I/O unit size (min_io_size) to the indicated write buffer size. By this change we intend to fix failed recovery of UBIFS partitions we currently observe on NOR flash when mounting the partition after unclean unmount. Currently the min_io_size is set to mtd->writesize (which is 1 byte for NOR flash). But flash programming is often done from prepared write buffer containing multiple bytes and is performed in one programming operation which could be interrupted by a power cut or a system reset causing corrupted (partially written) areas in a flash sector. Knowing the size of potentially corrupted areas UBIFS scanning and recovery algorithms are able to perform successful recovery. In case of NOR flash minimal I/O size must be equal to the maximal size of the write buffer used by embedded flash programming algorithm. In case of NAND flash mtd->writebufsize should be equivalent to mtd->writesize. The subsequent patches will add mtd->writebufsize initialization where needed. Signed-off-by: Anatolij Gustschin <agust@denx.de> --- include/linux/mtd/mtd.h | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-)