[i.MX28 GPMI] problem overwriting all-0xff data in NAND
b32955 at freescale.com
Mon Jul 18 22:12:20 EDT 2011
> On Mon, Jul 18, 2011 at 03:13:27PM +0200, Lothar Waßmann wrote:
>> 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).
>> encountered some problems with jffs2 when overwriting pages that have
>> been written with 0xff (e.g. from padding from the file system image
The GPMI driver now does not support the JFFS2 very well.
The JFFS2 will write the OOB, while the BCH of GPMI will use the OOB too.
So I have to disable the JFFS2 to use the OOB. I have not finish the
code about it now.
I recommend you use the UBIFS. But the latest version of GPMI driver
meets a DMA bug.
I am debugging the DMA bug now. and I will send it out when i fix it.
>> 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.
>> Any comments?
>> Lothar Waßmann
>> Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
>> Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
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>> www.karo-electronics.de | info at karo-electronics.de
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