Re: [PATCH v3 2/2] mtd: rawnand: brcmnand: improve hamming oob layout

Miquel Raynal
2020-05-12T07:20:04Z

Hi Álvaro,

Álvaro Fernández Rojas <noltari@gmail.com> wrote on Tue, 12 May 2020
09:12:10 +0200:

> Hi Miquel,
>
> I also had a hard time understanding your email.
> It was quite misleading.
>
> > El 12 may 2020, a las 9:08, Miquel Raynal <miquel.raynal@bootlin.com> escribió:
> >
> > Hi Álvaro,
> >
> > Álvaro Fernández Rojas <noltari@gmail.com> wrote on Tue, 12 May 2020
> > 08:00:23 +0200:
> >
> >> The current code generates 8 oob sections:
> >> S1 1-5
> >> ECC 6-8
> >> S2 9-15
> >> S3 16-21
> >> ECC 22-24
> >> S4 25-31
> >> S5 32-37
> >> ECC 38-40
> >> S6 41-47
> >> S7 48-53
> >> ECC 54-56
> >> S8 57-63
> >>
> >> Change it by merging continuous sections:
> >> S1 1-5
> >> ECC 6-8
> >> S2 9-21
> >> ECC 22-24
> >> S3 25-37
> >> ECC 38-40
> >> S4 41-53
> >> ECC 54-56
> >> S5 57-63
> >>
> >> Fixes: ef5eeea6e911 ("mtd: nand: brcm: switch to mtd_ooblayout_ops")
> >
> > Sorry for leading you the wrong way, actually this patch does not
> > deserve a Fixes tag.
>
> Do I need to resend this again?
> Looks like no matter what I do it’s always wrong...

Please don't give up! It is normal to work back and forth with the
community. I need the patch to be clear and bug-free so I ask you to
make changes and ask questions, that's how it works. But all your
patches are enhancing this driver so please keep posting!

>
> >
> >> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
> >> ---
> >> v3: invert patch order
> >> v2: keep original comment and fix correctly skip byte 6 for small-page nand
> >>
> >> drivers/mtd/nand/raw/brcmnand/brcmnand.c | 37 ++++++++++++------------
> >> 1 file changed, 18 insertions(+), 19 deletions(-)
> >>
> >> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> >> index 1c1070111ebc..0a1d76fde37b 100644
> >> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> >> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> >> @@ -1100,33 +1100,32 @@ static int brcmnand_hamming_ooblayout_free(struct mtd_info *mtd, int section,
> >> struct brcmnand_cfg *cfg = &host->hwcfg;
> >> int sas = cfg->spare_area_size << cfg->sector_size_1k;
> >> int sectors = cfg->page_size / (512 << cfg->sector_size_1k);
> >> + u32 next;
> >>
> >> - if (section >= sectors * 2)
> >> + if (section > sectors)
> >> return -ERANGE;
> >>
> >> - oobregion->offset = (section / 2) * sas;
> >> + next = (section * sas);
> >> + if (section < sectors)
> >> + next += 6;
> >>
> >> - if (section & 1) {
> >> - oobregion->offset += 9;
> >> - oobregion->length = 7;
> >> + if (section) {
> >> + oobregion->offset = ((section - 1) * sas) + 9;
> >> } else {
> >> - oobregion->length = 6;
> >> -
> >> - /* First sector of each page may have BBI */
> >> - if (!section) {
> >> - /*
> >> - * Small-page NAND use byte 6 for BBI while large-page
> >> - * NAND use bytes 0 and 1.
> >> - */
> >> - if (cfg->page_size > 512) {
> >> - oobregion->offset += 2;
> >> - oobregion->length -= 2;
> >> - } else {
> >> - oobregion->length--;
> >> - }
> >> + /*
> >> + * Small-page NAND use byte 6 for BBI while large-page
> >> + * NAND use bytes 0 and 1.
> >> + */
> >> + if (cfg->page_size > 512) {
> >> + oobregion->offset = 2;
> >> + } else {
> >> + oobregion->offset = 0;
> >> + next--;
> >
> > This next-- seems very strange, can you explain?
>
> In this case next will be 6 (which is the first ECC byte).
> However, for small page NANDs byte 5 is reserved for BBT, so we want next to be 5 only in this case.

That's clear, please add a comment there then.

>
> >
> >> }
> >> }
> >>
> >> + oobregion->length = next - oobregion->offset;
> >> +
> >> return 0;
> >> }
> >>
> >
> >
> > Thanks,
> > Miquèl
>
> Regards,
> Álvaro.

Thanks,
Miquèl