On 06-09-12 11:17 +1200, Andre Renaud wrote:
> When using YAFFS, is it possible to store the tags data in the page
> itself, rather than in the OOB area? I noticed a discussion a while ago
> regarding Samsung OneNAND, in which this method was suggested as a way
> of avoiding the restrictions that device placed on the OOB bytes. I have
> a chip with similar restrictions, which I can use fine to store straight
> data in, but not with YAFFS for the filesystem, due (I believe) to the
> OOB issues.
> 
> I assume that a similar method has to be taken when people use YAFFS
> with NOR flash (as has been mentioned in the list).
> 
> Has anyone worked on this? Is there a way to force YAFFS meta-data into
> the page area?

There isn't just a config option you can turn on - you'll need to mess
with the code. The YAFFS Direct Interface Guide has some details on what
is needed to make it work with NOR:
http://www.aleph1.co.uk/node/349
"Using YAFFS with NOR flash"

which shows how the data and oob info is simply put into NOR
sequentially.

For your setup you'll need to change YAFFS_BYTES_PER_CHUNK to be a bit smaller
than normal so there is room for the OOB bytes, then change the NAND
access functions to read/write to the right place. This is a lot
simpler if you aren't using MTD.

There may be some more wrinkles charles or others will comment on.

Wookey
-- 
Aleph One Ltd, Bottisham, CAMBRIDGE, CB5 9BA, UK  Tel +44 (0) 1223 811679
work: http://www.aleph1.co.uk/                 play: http://wookware.org/