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Date: Mon, 05 Dec 2011 17:09:00 +0000
From: Peter Horton <phorton@bitbox.co.uk>
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Subject: Re: [PATCH v2] MTD: modify mtd api to return bitflip info on read
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On 05/12/2011 16:58, Mike Dunn wrote:
> On 12/04/2011 10:07 PM, Artem Bityutskiy wrote:
>> On Sun, 2011-12-04 at 06:55 -0800, Mike Dunn wrote:
>>> So you're thinking that the driver would supply both ecc_strength and
>>> "scrublevel" (or maybe bb_threshold)?  Would these go into struct mtd_info?
>> Probably yes. After all, UBI has no idea about what kind of flash is
>> that and what kind of ECC it uses and what bit-flip level needs
>> scrubbing. So I think this kind of information should come from the
>> driver or from the user via mtd sysfs files. What do you think?
>
>
> I'm not a flash expert, but that sounds reasonable, especially if the scrublevel
> parameter is optional, with UBI using ecc_strength as the default value.  As for
> how to pass the parameter, sysfs might be a good idea for scrublevel, allowing
> it to be tunable without having to modify the driver if experience show that the
> driver author's original assumptions about how a block degrades were incorrect.
>

Surely the check for "do we need to scrub ?" should be done lower down 
otherwise all users of the mtd NAND interface (UBI / JFFS2 etc) are 
going to have to re-implement those sysfs files and the corresponding 
checks.

P.