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Date: Tue, 14 May 2013 10:23:51 +0800
From: Huang Shijie <b32955@freescale.com>
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To: Vikram Narayanan <vikram186@gmail.com>
Subject: Re: mtd_oobtest fails with GPMI-NAND
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=E4=BA=8E 2013=E5=B9=B405=E6=9C=8814=E6=97=A5 00:51, Vikram Narayanan =E5=
=86=99=E9=81=93:
> 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=20
>> 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=20
> providing a _sane_ ecclayout structure, so that the mtd_tests run=20
> happily?
>
could you please read the chapter about the BCH, especially the "Flash=20
Page Layout".

The reason why We use all the oob is that we can not get the correct ECC=20
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=20
ONFI nand and full-id nand.

The gpmi-nand does not live for mtd_tests. If it can not pass some=20
mtd_tests, it does not mean the gpmi has bugs.



thanks
Huang Shijie



> Regards,
> Vikram
>