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Subject: Re: [PATCH] omap : nand : fix subpage ecc issue with prefetch
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Vimal Singh <vimal.newwork@gmail.com>
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Date: Fri, 06 May 2011 21:56:17 +0300
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Cc: bdefaria@adeneo-embedded.com, linux-mtd@lists.infradead.org,
	linux-omap@vger.kernel.org, Kishore Kadiyala <kishore.kadiyala@ti.com>
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On Fri, 2011-05-06 at 13:00 +0530, Vimal Singh wrote:
> On Fri, May 6, 2011 at 12:18 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > On Mon, 2011-05-02 at 16:40 +0530, Kishore Kadiyala wrote:
> >> For prefetch engine, read and write  got broken in commit '2c01946c'.
> >> We never hit a scenario of not getting 'gpmc_prefetch_enable'
> >> call success.
> >> When reading/writing a subpage with a non divisible by 4 ecc number
> >> of bytes, the mis-aligned bytes gets handled first before enabling
> >> the Prefetch engine, then it reads/writes rest of the bytes.
> >>
> >> Signed-off-by: Kishore Kadiyala <kishore.kadiyala@ti.com>
> >> Signed-off-by: Vimal Singh <vimal.newwork@gmail.com>
> >> Reported-by: Bryan DE FARIA <bdefaria@adeneo-embedded.com>
> >
> > This needs a better commit message with more explanation and analysis of
> > the problem and how it was fixed.This commit message is not very
> > understandable. And then it needs also:
> 
> How about a commit log like this:

Looks better, thanks. Waiting for the new patch.

> 
> When reading/writing a subpage (When HW ECC is not available/enable)
> for number of bytes not aligned to 4, the mis-aligned bytes gets
> handled first (by cpu copy mathod) before enabling the Prefetch
> engin to/from 'p' (start of buffer 'buf').
> Then it reads/writes rest of the bytes with the help of Prefetch
> engine, if available, or again by cpu copy mathod. Currnetly,
> reading/writing of rest of bytes, is not done correctly. Its trying to
> read/write again to/from begining of buffer 'buf', overwriting the
> mis-aligned bytes.
> 
> For prefetch engine read and write it got broken in commit '2c01946c'.
> And we never hit the scenario of not getting 'gpmc_prefetch_enable'
> call sucess. So, problem did not get caught up.
> 
> This patch fixes the issue.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)