[Yaffs] yaffs2 on onenand

[Charles Manning]

On Saturday 17 June 2006 01:00, Naushad K wrote:
> Hi,
>
> Did any one tried to use yaffs2  on onenand ?
>
> When I looked at the onenand_base.c, the oobinfo is as per  the
> following format.
>
>
> /**
>  * onenand_oob_64 - oob info for large (2KB) page
>  */
> static struct nand_oobinfo onenand_oob_64 = {
> 	.useecc		= MTD_NANDECC_AUTOPLACE,
> 	.eccbytes	= 20,
> 	.eccpos		= {
> 		8, 9, 10, 11, 12,
> 		24, 25, 26, 27, 28,
> 		40, 41, 42, 43, 44,
> 		56, 57, 58, 59, 60,
> 		},
> 	.oobfree	= {
> 		{2, 3}, {14, 2}, {18, 3}, {30, 2},
> 		{24, 3}, {46, 2}, {40, 3}, {62, 2} }
> };
>
>
> But I have not seen code in onenand_base.c for doing the autoplace
> of the yaffs tags into the oobfree area as  its there in nand_base.c
>
> Can the yaffs2 work with current onenand_base.c ?

I don't think so.

I am not sure about what goes on in the mtd for onenand, but it would have to 
make the oob free space available.

The other problem is that the current yaffs_PackedTags2 requires approx 28 
bytes for the tag area. The above only provides 20 bytes.

It would be possible to make yaffs work on OneNAND by one of two possible 
routes:
1) Reduce the size of the packed tags structure to fit. This would require mtd 
to suport free oob bytes.
2) Use a differeeent chunk layout that places the tags in the page rather than 
in the oob. This would not require mtd to support free oob bytes.

-- Charles