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Subject: Re: CONFIG_MTD_NAND_VERIFY_WRITE with Software ECC
From: Artem Bityutskiy <dedekind1@gmail.com>
To: David Peverley <pev@sketchymonkey.com>
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Date: Fri, 25 Feb 2011 15:21:49 +0200
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Cc: "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	Ivan Djelic <ivan.djelic@parrot.com>,
	Ricard Wanderlof <ricard.wanderlof@axis.com>
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On Fri, 2011-02-25 at 12:59 +0000, David Peverley wrote:
> Hi All,
> 
> > How about changing the MTD interface a little and teach it to:
> > 1. Report the bit-flip level (or you name it properly) - the amount of
> > bits flipped in this NAND page (or sub-page). If we read more than one
> > NAND page at one go, and several pages had bit-flips of different level,
> > report the maximum.
> This is important to allow the file-system to make an informed
> decision based on what happened within MTD. i.e. it would be able to
> ascertain whether a read corrected N bit errors and thus be able to
> re-program a block as required. I think is the only way to accomplish
> handling this at the FS level? However, given that the count comes
> from a specific read operation, I think it would need to be
> implemented as part of the read call e.g. passing in something like
> "unsigned *bit_errors"? This would mean changing something fundamental
> or providing a new API to read with this extra parameter so I'm not
> sure how this could be accomplished 'nicely'...

I do not think it is an issue - changing in-kernel API is relatively
easy and straight-forward task.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)