From 0e4ca7e5101e7f4054452b8d71c535eec64a187b Mon Sep 17 00:00:00 2001 From: Anatolij Gustschin Date: Thu, 16 Dec 2010 23:42:14 +0100 Subject: [PATCH] mtd: add writebufsize field to mtd_info struct 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 Signed-off-by: Artem Bityutskiy Signed-off-by: David Woodhouse --- include/linux/mtd/mtd.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index fe8d77ebec1..9d5306bad11 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -144,6 +144,17 @@ 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. Currently, all NANDs have writebufsize + * equivalent to writesize (NAND page size). Some NOR flashes do have + * writebufsize greater than writesize. + */ + uint32_t writebufsize; + uint32_t oobsize; // Amount of OOB data per block (e.g. 16) uint32_t oobavail; // Available OOB bytes per block -- 2.39.5