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

Álvaro Fernández Rojas
2020-05-12T07:12:18Z

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...

>
>> 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.

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

Regards,
Álvaro.