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Date: Thu, 8 Nov 2012 14:22:50 -0500
From: Christopher Harvey <charvey@matrox.com>
To: Ivan Djelic <ivan.djelic@parrot.com>
Subject: Re: state of support for "external ECC hardware"
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On Thu, Nov 08, 2012 at 07:59:42PM +0100, Ivan Djelic wrote:
> On Thu, Nov 08, 2012 at 03:21:25PM +0000, Christopher Harvey wrote:
> (...) 
> > We had BCH8 code running, but it wasn't enough. The main reason we
> > switched away from host side ECC was because we were getting bitflips
> > within the ECC codeword data itself.
> 
> But the ECC bytes are part of the BCH codeword, therefore I don't understand
> what the issue could be ? Are you sure bitflips were not in some unprotected
> OOB area ?

Ok, the ECC bytes I had were stored in the OOB area and were
unprotected. Any bit flips in the OOB area was a disaster. This was
coming from a heavily modified forked kernel that had BCH8 bugs in the
past. For example, I had to fix this one before the patch came out:
http://arago-project.org/git/projects/linux-omap3.git?p=projects/linux-omap3.git;a=commitdiff;h=adc46d691d745604da1197d154fe712e10ec468d;hp=9e78267ed6302537474489e88bd59827315db15b
I can't explain why this implementation fails on ECC byte corruption.

-Chris