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

[Shawn Guo]

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.
> 
> Any comments?
> 
> 
> Lothar Waßmann
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