[i.MX28 GPMI] problem overwriting all-0xff data in NAND

[Huang Shijie]

Hi Lothar:
> On Mon, Jul 18, 2011 at 03:13:27PM +0200, Lothar Waßmann wrote:
>> Hi,
>>
>> with the gpmi-nfc driver for imx28 from Shawn Guo on a TX28 I
> To be clear, the author of gpmi-nfc driver is Huang Shijie (Cc-ed).
>
> Regards,
> Shawn
>
>> encountered some problems with jffs2 when overwriting pages that have
>> been written with 0xff (e.g. from padding from the file system image
>> file).
>>
>> The problem is that the ECC info for an all-0xff block is not all-0xff
>> and thus a newly erased block is different from a block that has been
>> written with 0xff.
>> If such a block is being altered (jffs2 thinking it can simply
>> overwrite it without erasing first) the ECC information will be
>> corrupted and will produce ECC errors upon read.
>>
>> The only remedy I can think of is to prevent empty pages from actually
>> being written to flash, but leaving them in the erased state instead.
Did you mean that:
If the gpmi have to write a page which is full of 0xff,
the gpmi driver should skip the writting, and leave the page in the 
erased state.

Am I right?

Huang Shijie
>> Any comments?
>>
>>
>> Lothar Waßmann
>> -- 
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