Re: [RFC/PATCH v2] S3C24xx: NAND management changes to support booting from NAND

[Juergen Beisert <jbe@pengutronix.de>]

Baruch Siach wrote:
> On Mon, Mar 07, 2011 at 10:18:00AM +0100, Juergen Beisert wrote:
> > Juergen Beisert wrote:
> > > This is revision two of my patch series to make the mini2440 booting
> > > from NAND. This seems somehow tricky: The mini2440 with a 64 MiB NAND
> > > works fine here, but the one with 128 MiB does currently boot only.
> > > In the first patch series where some errors in page address
> > > calculation, so they cannot work. This patch series might do it in a
> > > correct manner, but now only tested on 64 MiB and 128 MiB NAND. At
> > > least booting from NAND is now working also from 128 MiB. But the ECC
> > > handling fails, and I have no idea whats wrong now: Reading the
> > > environment fails with 'err: -74'...
> >
> > Here the main question:
> > - what is the difference in ECC handling in the S3C2440 CPU when using
> >   a "small page" or a "large page" NAND?
> >   "Small page" ECC seems to work, but "large page" ECC fails. Anyone here
> > with more experience with S3C2440/NAND? The Linux driver works well on
> > the large page NANDs, but not the barebox's one.
>
> I don't have experience with the S3C2440 NAND controller, but I'm working
> on a similar problem in the i.MX NAND controller Linux driver. NAND chips
> with 2k page size work fine, but 4k devices fail in the kernel. The cause
> for this is the wrong nand_ecclayout. In the i.MX case, the .eccpos table
> was too small for the larger ECC table of the 4k devices. This caused a
> corruption of the OOB data at the higher level of the NAND stack. Fixing
> this requires upgrade to a newer kernel (I currently use 2.6.36).
>
> As the nand_s3c2410 Barebox driver (like the kernel one) has only one
> nand_ecclayout struct for the 512 bytes page size, this may be the cause of
> your problem.
>
> I hope this helps.

\o/ The S3C2440 is using a 4 bytes ECC for 2048 sized page NANDs. After 
changing it, barebox is now able to write and read the environment.

Thanks,
jbe

-- 
Pengutronix e.K.                              | Juergen Beisert             |
Linux Solutions for Science and Industry      | Phone: +49-8766-939 228     |
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