U-boot bch4_sw vs omap bch4_hw

Andreas Bießmann andreas.biessmann at corscience.de
Mon Dec 10 05:35:02 EST 2012

Hi Ivan Djelic and Jean-Philippe Francois,

On 10.12.2012 10:41, jean-philippe francois wrote:
> 2012/12/8 Ivan Djelic <ivan.djelic at parrot.com>:
>> On Fri, Dec 07, 2012 at 03:26:06PM +0000, jean-philippe francois wrote:
>>> Hi Ivan,
>>> I have applied your patches for hardware bch ecc support on
>>> OMAP. On the linux side, everything is fine. However I have some trouble
>>> when it comes to u-boot and kernel interoperability.
>>> A nand page written with bch4_sw ecc by U-boot fails the ecc step when
>>> read by the kernel. Looking at a nanddump, OOB placement and size of
>>> the ecc data are the same.
>>> Do you know of any patch for u-boot that would make the  bch4_sw ecc
>>> identical to the kernel one ?

can you both please have a loot at

>> Hi Jean-Philippe,
>> If you point me to a git repo with the exact u-boot version you are using,
>> I can probably provide a patch (or at least understand the problem).
>> BR,
>> --
>> Ivan
> I am using an u-boot from the arago project :
> http://arago-project.org/git/projects/?p=u-boot-omap3.git;a=tags
> So it is quite old.
> I will probably have to modify x-loader, too.

current u-boot do not need x-loader any more.

> Both implementation use very similar file for hardware assisted
> bch decoding.
> If this code is too old for you to look at, could you help me find an omap
> project that "new ecc" all the way up from x-loader to u-boot + kernel ?
> If I understands things correctly, I have two options if I want to use
> Nand that needs
> 4-bit ecc :
> - Stick with the old ecc scheme in x-loader and u-boot, and use
> software 4-bit bch in the kernel.
>   Is this compatible with using ubifs ?
> - Implement new ecc scheme in x-loader and u-boot, and use hardware
> assisted bch-4 in the kernel.
> Is this correct ?

 * use 1-bit hamming 'ROM-layout' for SPL mtd and 4-bit BCH8 in all
other sections, see my u-boot patches.

Would be great to have some testers for these patches.

Best regards

Andreas Bießmann

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