[U-Boot] [PATCH] mxs_nand: Fix ECC strength for NAND flash with OOB size of 256

[Heiko Schocher]

Hello Joerg,

Am 13.04.2015 13:38, schrieb Jörg Krause:
> Hi Marek, Heiko,
>
> On Mo, 2015-04-13 at 11:01 +0200, Heiko Schocher wrote:
>> Hello Marek, Joerg,
>>
>> Am 13.04.2015 10:42, schrieb Marek Vasut:
>>> On Monday, April 13, 2015 at 10:39:46 AM, Jörg Krause wrote:
>>>> Hi Heiko,
>>>>
>>>> On So, 2015-04-12 at 10:17 +0200, Heiko Schocher wrote:
>>>>> On the i.mx6 based aristainetos2 board a Toshiba
>>>>> TH58NYG3S0HBAI4
>>>>> is used, which has 4096 pagesize and 256b oob. The ECC strength
>>>>> was not correct detected by U-Boot
>>>>>
>>>>> Signed-off-by: Heiko Schocher <hs at denx.de>
>>>>> ---
>>>>>
>>>>>    drivers/mtd/nand/mxs_nand.c | 3 +++
>>>>>    1 file changed, 3 insertions(+)
>>>>>
>>>>> diff --git a/drivers/mtd/nand/mxs_nand.c
>>>>> b/drivers/mtd/nand/mxs_nand.c
>>>>> index 2d2b938..00bf036 100644
>>>>> --- a/drivers/mtd/nand/mxs_nand.c
>>>>> +++ b/drivers/mtd/nand/mxs_nand.c
>>>>> @@ -163,6 +163,9 @@ static inline uint32_t
>>>>> mxs_nand_get_ecc_strength(uint32_t page_data_size,
>>>>>
>>>>>                 if (page_oob_size == 224)
>>>>>
>>>>>                         return 16;
>>>>>
>>>>> +
>>>>> +             if (page_oob_size == 256)
>>>>> +                     return 18;
>>>>>
>>>>>         }
>>>>>
>>>>>         return 0;
>>>>
>>>> How about calculation the ECC strength dynamically? Peng Fan from
>>>> Freescale send a patch doing this in December 2014 which was
>>>> already
>>>> reviewed by Marek:
>>>> https://patchwork.ozlabs.org/patch/422756/
>>>>
>>>> It is also necessary to change the calculation in mxsboot...
>>>
>>> Would be nice if the patch got applied, but I think there were some
>>> comments and the patch was never fixed/reposted. If Heiko wants to
>>> do it, that'd be nice.
>>
>> Hmm.. I feel, I have not much time left for fixing such things...
>
> I can re-submit the patch from Peng Fan together with my fixes for
> mxsboot.

Yes, please (and with a comment for the magic number 13 ;-)

I can test your patches then on an imx6 based board ... maybe we
do not need my patch then!

>> Joerg: You wrote on Jan. 27, 2015, 11:14 p.m.:
>> "I was able to fix mxsboot, but I had difficulties with round_down,
>> which
>> is a macro definition in linux/kernel.h. I've copied the macro
>> definition to mxsboot. I will submit the patch in a seperate mail."
>>
>> Did you post such a patch? Was this the onyl problem of the patch
>> from Peng Fan?
>
> No, I didn't. I waited for some comment and then I just forgot about
> it. The main problem with the patch from Peng Fan was that it was not
> consistent with mxsboot, which still has the hardcoded oobsizes. I
> copied the calculation to mxsboot.c, but failed to include
> linux/kernel.h, because mxsboot is compiled with the host compiler and
> u-boot with the cross-compiler. So I just copied the macro definition
> for round_down from kernel.h to mxsboot.c.
>
>> "I would like to see a comment or a macro for the magic number 13,
>> which
>> is the value for the Galois Field, just for clarification"
>>
>> I have no idea what 13 means ...
>
> This is cited from the i.MX28 Reference Manual:
>      BCH-codes are a type of block-code, which implies that all error-
>      correction is performed over a block of N-symbols. The BCH
>      operation will be performed over GF (2^13 = 8192), which is the
>      Galois Field consisting of 8191 one-bit symbols.

Thanks!

bye,
Heiko
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