On Fri, 25 Nov 2016 10:58:26 +0100
Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> On 11/25/2016 10:13 AM, Boris Brezillon wrote:
> > Commit a894cf6c5a82 ("mtd: nand: mxc: switch to mtd_ooblayout_ops")
> > introduced a bug in the OOB layout description. Even if the driver claims
> > that 3 ECC bytes are reserved to protect 512 bytes of data, it's actually
> > 5 ECC bytes to protect 512+6 bytes of data (some OOB bytes are also
> > protected using extra ECC bytes).
> >
> > Fix the mxc_v1_ooblayout_{free,ecc}() functions to reflect this behavior.
> >
> > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> > Fixes: a894cf6c5a82 ("mtd: nand: mxc: switch to mtd_ooblayout_ops")
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > ---
> > drivers/mtd/nand/mxc_nand.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
> > index 61ca020c5272..c19ec4f0983e 100644
> > --- a/drivers/mtd/nand/mxc_nand.c
> > +++ b/drivers/mtd/nand/mxc_nand.c
> > @@ -886,7 +886,7 @@ static int mxc_v1_ooblayout_ecc(struct mtd_info *mtd, int section,
> > return -ERANGE;
> >
> > oobregion->offset = (section * 16) + 6;
> > - oobregion->length = nand_chip->ecc.bytes;
> > + oobregion->length = 5;
>
> Use a macro instead of hard-coding a value please :)
Ideally, we should change ->eccbytes value in the
imx27_nand_devtype_data and imx21_nand_devtype_data definitions, but I
fear it could break other things.
I'll define a macro.
>
> > return 0;
> > }
> > @@ -908,8 +908,7 @@ static int mxc_v1_ooblayout_free(struct mtd_info *mtd, int section,
> > oobregion->length = 4;
> > }
> > } else {
> > - oobregion->offset = ((section - 1) * 16) +
> > - nand_chip->ecc.bytes + 6;
> > + oobregion->offset = ((section - 1) * 16) + 5 + 6;
>
> DTTO here, the math here is cryptic enough.
>
> > if (section < nand_chip->ecc.steps)
> > oobregion->length = (section * 16) + 6 -
> > oobregion->offset;
> >
>
>
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