From 6d77b9d0af57409c918ab9501866233082546ba6 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Wed, 7 Sep 2011 13:13:40 -0700 Subject: [PATCH] mtd: nand: invalidate cache on unaligned reads In rare cases, we are given an unaligned parameter `from' in `nand_do_read_ops()'. In such cases, we use the page cache (chip->buffers->databuf) as an intermediate buffer before dumping to the client buffer. However, there are also cases where this buffer is not cleanly reusable. In those cases, we need to make sure that we explicitly invalidate the cache. This patch prevents accidental reusage of the page cache, and for me, this solves some problems I come across when reading a corrupted BBT from flash (NAND_BBT_USE_FLASH and NAND_BBT_NO_OOB). Note: the rare "unaligned" case is a result of the extra BBT pattern + version located in the data area instead of OOB. Also, this patch disables caching on raw reads, since we are reading without error correction. This is, obviously, prone to errors and should not be cached. Signed-off-by: Brian Norris Signed-off-by: Artem Bityutskiy --- drivers/mtd/nand/nand_base.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index c9767b5..51653d9 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -1479,14 +1479,22 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from, else ret = chip->ecc.read_page(mtd, chip, bufpoi, page); - if (ret < 0) + if (ret < 0) { + if (!aligned) + /* Invalidate page cache */ + chip->pagebuf = -1; break; + } /* Transfer not aligned data */ if (!aligned) { if (!NAND_SUBPAGE_READ(chip) && !oob && - !(mtd->ecc_stats.failed - stats.failed)) + !(mtd->ecc_stats.failed - stats.failed) && + (ops->mode != MTD_OPS_RAW)) chip->pagebuf = realpage; + else + /* Invalidate page cache */ + chip->pagebuf = -1; memcpy(buf, chip->buffers->databuf + col, bytes); } -- 2.7.4