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

Álvaro Fernández Rojas
2020-05-12T07:26:34Z

Hi Miquèl,

> El 12 may 2020, a las 9:19, Miquel Raynal <miquel.raynal@bootlin.com> escribió:
>
> 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.

Isn’t “Small-page NAND use byte 6 for BBI while large-page NAND use bytes 0 and 1.” enough?
Do we really need a specific comment before next--?

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

Regards,
Álvaro.