[U-Boot] BCH8 support when we do not have ELM h/w engine.

[Enric Balletbo Serra]

2013/12/4 Enric Balletbo Serra <eballetbo at gmail.com>:
> Dear Pekon,
>
> I'm trying to enable the support for BCH8 for platforms that do not
> have ELM hardware engine. Maybe I'm missing something but my first and
> quick attempt was applying the following patch:
>
>   http://pastebin.com/VUjuGChR
>
> With this patch I'm able to switch to
> OMAP_ECC_BCH8_CODE_HW_DETECTION_SW with the nandecc hw bch8 command.
>
> Then I tried to flash a ubi rootfs into the nand, but the kernel can't
> mount the filesystem, I see messages like that:
>
> [    3.703582] ecc unrecoverable error
> [    3.707244] UBI warning: ubi_io_read: error -74 (ECC error) while
> reading 64 bytes from PEB 2:0, read only 64 bytes, retry
>
> OTOH, if I flash the rootfs from the kernel (my board sets the ecc to
> bch8) I don't have any problem, I can mount without problems.
>
> I saw that the OOB layout is not the same when I flash the rootfs from
> the u-boot or from the kernel. For example:
>
> If the rootfs is flashed from the kernel the OOB data is like that:
>
> U-Boot # nand dump.oob 0x680000
> Page 00680000 dump:
> OOB:
>     ff ff 79 43 68 64 3b 80
>     b2 46 49 4d 58 2a 6d ff
>     52 3f 7d 2a 7f a2 98 70
>     57 32 30 35 c7 ff ff ff
>     ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff
>
> If the rootfs is flashed for the u-boot the OOB data is like data:
>
> Page 00680000 dump:
> OOB:
>     ff ff 79 43 68 64 3b 80
>     b2 46 49 4d 58 2a 6d 52
>     3f 7d 2a 7f a2 98 70 57
>     32 30 35 c7 ff ff ff ff
>     ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff
>     ff ff ff ff ff ff ff ff
>
> Note that look the same except after byte number 16. In the first case is
>     ff 52 3f 7d 2a 7f a2 98 70
> and in the second case is
>     52 3f 7d 2a 7f a2 98 70
>
> It's possible that something is wrong writting the OOB data ? Any clue
> ? I'm in the right direction or completely wrong ?
>
> Thanks in advance,
>    Enric

Any clue about this ?