> -----Original Message-----
> From: yaffs-bounces@lists.aleph1.co.uk [mailto:yaffs-
> bounces@lists.aleph1.co.uk] On Behalf Of Eddie Dawydiuk
> Sent: Friday, 4 December 2009 9:53 AM
> To: yaffs@lists.aleph1.co.uk
> Subject: [Yaffs] MLC support
>
> Hello,
>
> I've seen on the Yaffs homepage it is mentioned MLC support is under
> development. Although, I've also seen some people on the mailing list
> already
> running Yaffs2 on MLC. I'm assuming Yaffs2 will add Reed-Solomon
support
> for
> MLC, will there be other changes required?
>
I believe the primary change in Yaffs2 is the avoidance of page
reprogramming: Yaffs1 needed to clear the 'valid' bit in existing pages
in order to delete them. Yaffs2 uses a sequence number and an extra
scan, so each page is programmed once and exactly once (until a block
erase). MLC likes this better.
I'm pretty sure Yaffs2 does not add Reed-Solomon ECC support *directly*
- on my particular platform, performing RS in software would chew too
much CPU, and there's a hardware accelerator instead - but the Yaffs2
tag structure and larger logical page size makes it actually *possible*
to use RS ECC when it's implemented by the MTD/NAND driver.
J
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