On Thursday 10 May 2007, David Goodenough wrote:
> On Wednesday 09 May 2007, Charles Manning wrote:
> > If you're getting ECC errors here it is possibly because the flash has
> > been written using yaffs_ecc.c and read (with nand_dump) using mtd's
> > nand_ecc.c
> >
> > nand_ecc.c generates exaclty the same data as yaffs_ecc.c, but the byte
> > ordering is different. Both implement the SmartMedia ECC mechanism, but
> > the byte order is broken in nand_ecc.c
>
> Reading this I thought that I would look at the config options for MTD. 
> And sure enough there is one (that was not set) called
> CONFIG_MTD_NAND_ECC_SMC which was not set.  So I tried setting it, but it
> does not seem to make any difference - I get the same problems.
Actually, looking at the code there is a typo in nand_ecc.c.  It uses
CONFIG_NAND_ECC_SMC not CONFIG_MTD_NAND_ECC_SMC.  This is fixed in 2.6.20
but not in 2.6.19.  So I have put my own patch in to fix that, and I am 
rebuilding my kernel as I type.  But I have to pop out for an hour or so
so I will report when I return.

David
>
> When I mount the partition, all the blocks are flaged as bad and when I use
> nanddump it complains about uncorrectable bitflips just as before.
>
> What change is needed to nand_ecc.c to get the byte order the same as
> yaffs_ecc.c.  A brief look had them looking very similar, but of course I
> may have missed something.
>
> David
>
> > There are two solutions to this mess:
> > 1) Microtik should provide their driver configs under GPL.
> > 2) Trace through the data reading/writing to see where the OOB byte
> > ordering is getting screwed up.
>
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