Messages in this thread Patch in this message | | | Date | Fri, 8 Jun 2012 18:41:26 +0300 | From | Shmulik Ladkani <> | Subject | [PATCH] mtd: nand: Properly initialize 'mtd->bitflip_threshold' prior 'scan_bbt()' is invoked |
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As of edbc454 [mtd: driver _read() returns max_bitflips; mtd_read() returns -EUCLEAN], 'mtd->bitflip_threshold' must be set for mtd devices having ECC, prior any 'mtd_read()' call. Otherwise, 'mtd_read()' will falsely return -EUCLEAN.
Normally, 'mtd->bitflip_threshold' is initialized when the MTD is added.
However, this is too late for NAND MTDs, as 'scan_bbt()' is invoked prior the existing initialization of 'mtd->bitflip_threshold'.
This is a problem since 'scan_bbt()' calls 'mtd_read()', in the case of a flash-based bad block table. It resulted in a falsely reported bitflips indication during BBT read, which lead to constant scrubbing of the flash BBT blocks.
Initialize 'mtd->bitflip_threshold' to its default value (if not already set by the driver), prior invocation of 'scan_bbt()'.
Reported-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> --- - The issue was introduced in v3.5-rc1, and needs to be merged prior v3.5 - Sascha, I've credited you as reporter, is that ok with you? - Sashca, care to test the fix on your system?
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 61805e7..0a8724e 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -3484,6 +3484,13 @@ int nand_scan_tail(struct mtd_info *mtd) /* propagate ecc info to mtd_info */ mtd->ecclayout = chip->ecc.layout; mtd->ecc_strength = chip->ecc.strength; + /* + * Initialize bitflip_threshold to its default prior scan_bbt() call. + * scan_bbt() might invoke mtd_read(), thus bitflip_threshold must be + * properly set. + */ + if (!mtd->bitflip_threshold) + mtd->bitflip_threshold = mtd->ecc_strength; /* Check, if we should skip the bad block table scan */ if (chip->options & NAND_SKIP_BBTSCAN) -- 1.7.5.4
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