mtd_oobtest fails with GPMI-NAND

[Huang Shijie]

于 2013年05月14日 00:51, Vikram Narayanan 写道:
> Hello Huang,
>
> On 5/13/2013 2:31 PM, Huang Shijie wrote:
>>>
>>> Huang, is this to be expected? How does this look on one of your
>>> officially "supported" imx6 boards with NAND support?
>>>
>> I suggest you do not use the mtd_nandbiterrs.ko. It will call the
>> mtd_write_oob() which will definitely lead to the
>> -EBADMSG (-74) error.
>>
>> The mtd_write_oob() in mtd_nandbiterrs.ko writes a whole page without
>> enabling the BCH to do the hardware ECC.
>> But mtd_read() in mtd_nandbiterrs.ko DOES do the hardware ECC by the 
>> BCH.
>> It's normal that you meet -74.
>
> I wonder if this has something to do with the fake
> "struct nand_ecclayout" defined in
> <drivers/mtd/nand/gpmi-nand/gpmi-nand.c>?
it's not a fake structure, i think.

We do use all the oob now.
>
> Could you please explain on what is the technical restriction for not 
> providing a _sane_ ecclayout structure, so that the mtd_tests run 
> happily?
>
could you please read the chapter about the BCH, especially the "Flash 
Page Layout".

The reason why We use all the oob is that we can not get the correct ECC 
info from the nand, such as "4 bits for 512 byte".
I have sent a patch set with whitch we can parse out some ECC info for 
ONFI nand and full-id nand.

The gpmi-nand does not live for mtd_tests. If it can not pass some 
mtd_tests, it does not mean the gpmi has bugs.



thanks
Huang Shijie



> Regards,
> Vikram
>