[PATCH] mtd: nand: Properly initialize 'mtd->bitflip_threshold' prior 'scan_bbt()' is invoked

[Shmulik Ladkani]

Artem, David,

Patch was accidentally submitted twice.

Disregard this post please.

Sorry for the inconvenience.

Regards,
Shmulik

On Fri, 8 Jun 2012 18:29:06 +0300 Shmulik Ladkani <shmulik at jungo.com> wrote:
> 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 at pengutronix.de>
> Signed-off-by: Shmulik Ladkani <shmulik.ladkani at gmail.com>