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Date: Fri, 12 Apr 2013 11:12:42 +0200
From: =?ISO-8859-1?Q?Steffen_K=FChn?= <sk@ammonit.com>
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To: David Mosberger-Tang <dmosberger@gmail.com>
Subject: Re: Changing the ECC method for a running system (UBI seems to use
 OOB?)
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Hello David,

> We had exactly the same issue with our embedded systems (I'm really mad at
> Micron that they released the 4-bit ECC chips without as much as putting a
> warning message in the Linux kernel, but that's a separate topic...).
> 
> Anyhow, we modified the AT91bootstrap loader to convert the entire NAND
> from 1-bit sw-ecc to on-die 4-bit ECC.  I'd be happy to send a patch to
> this mailing list if you think this would be useful.

Yes, this would be great! The patch is certainly also helpful for the
next with the same problem ...

> 
> UBI fortunately does not use OOB at all, so there should be no issue from
> there.
I have read this too. I'm happy that I have not to deal with YAFFS2.

> 
> The subpage size has to match though.  In our case, UBI was built for 512B
> subpage, but when turning on the on-die ECC support, it'd by default only
> support 2048B pages.  The patch I sent earlier to this mailing list enables
> 512B subpage writes with on-die ECC.

That could be my problem. I have not considered this point. Thanks!

Best regards,
Steffen