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Date: Fri, 8 Jun 2012 19:17:41 +0300
From: Shmulik Ladkani <shmulik.ladkani@gmail.com>
To: David Woodhouse <dwmw2@infradead.org>, Artem Bityutskiy
 <artem.bityutskiy@linux.intel.com>
Subject: Re: [PATCH] mtd: nand: Properly initialize 'mtd->bitflip_threshold'
 prior 'scan_bbt()' is invoked
Message-ID: <20120608191741.3877cd3a@halley>
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References: <20120608182906.57b4844a@halley>
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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@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@pengutronix.de>
> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>