[PATCH] mtd: nand: Add support for Micron on-die ECC controller (rev2).

[David Mosberger]

On Thu, Mar 27, 2014 at 12:56 AM, Gupta, Pekon <pekon at ti.com> wrote:

>>+      set_on_die_ecc(mtd, chip, 1);
>>+
>>+      chkoob = chkbuf + mtd->writesize;
>>+      rawoob = rawbuf + mtd->writesize;
>>+      eccpos = chip->ecc.layout->eccpos;
>>+      for (i = 0; i < chip->ecc.steps; ++i) {
>>+              /* Count bit flips in the actual data area: */
>>+              flips = bitdiff(chkbuf, rawbuf, chip->ecc.size);
>>+              /* Count bit flips in the ECC bytes: */
>>+              for (j = 0; j < chip->ecc.bytes; ++j) {
>
> You should check bit-flips in complete OOB region (mtd->oobsize) not just ecc.bytes.

I was under the impression that OOB data bytes cannot be assumed to be
ECC protected.
As it happens, when using Internal ECC on those Micron chips, *some*
of the OOB databytes
are ECC protected, but I didn't think it was necessary to count those
for bitflips, since OOB users
won't assume ECC protection anyhow.  Am I wrong about that?

  --david
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