Re: Problem with clean markers/partial writes on Micron 4-bit ECC NAND

[Artem Bityutskiy <dedekind1@gmail.com>]

On Fri, 2011-06-17 at 13:52 -0400, Peter Barada wrote:
> I'm using a 2K page Micron NAND that has an internal 4-bit ECC engine.
> 
> The Micron NAND chip uses 8-bytes per 512 bytes of main data area + 4 
> bytes of the OOB.  This allows the 32 bytes of ECC to correct 2048 bytes 
> of the main data area and 16 bytes of the OOB area.
> 
> The problem I'm running into with JFFS2 is that empty flash is first 
> marked with a clean marker into the OOB, and then a 2nd write to the 
> main data area is done (w/o an intervening erase) to that page with data 
> which corrupts the ECCs that were first modified by writing the cleanmarker.

I remember someone sent patches to teach JFFS2 to avoid using clean
markers, but I do not remembers the details and whether the patches made
it into the mainline.

-- 
Best Regards,
Artem Bityutskiy