Messages in this thread Patch in this message | | | Date | Wed, 12 Apr 2023 18:51:18 +0800 | Subject | Re: [PATCH v1 4/5] mtd: rawnand: meson: clear OOB buffer before read | From | Liang Yang <> |
| |
Hi Arseniy and Miquel,
On 2023/4/12 18:14, Arseniy Krasnov wrote: > [ EXTERNAL EMAIL ] > > > > On 12.04.2023 12:36, Miquel Raynal wrote: >> Hi Arseniy, >> >> avkrasnov@sberdevices.ru wrote on Wed, 12 Apr 2023 12:20:55 +0300: >> >>> On 12.04.2023 10:44, Miquel Raynal wrote: >>>> Hi Arseniy, >>>> >>>> AVKrasnov@sberdevices.ru wrote on Wed, 12 Apr 2023 09:16:58 +0300: >>>> >>>>> This NAND reads only few user's bytes in ECC mode (not full OOB), so >>>> >>>> "This NAND reads" does not look right, do you mean "Subpage reads do >>>> not retrieve all the OOB bytes,"? >>>> >>>>> fill OOB buffer with zeroes to not return garbage from previous reads >>>>> to user. >>>>> Otherwise 'nanddump' utility prints something like this for just erased >>>>> page: >>>>> >>>>> ... >>>>> 0x000007f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>> OOB Data: ff ff ff ff 00 00 ff ff 80 cf 22 99 cb ad d3 be >>>>> OOB Data: 63 27 ae 06 16 0a 2f eb bb dd 46 74 41 8e 88 6e >>>>> OOB Data: 38 a1 2d e6 77 d4 05 06 f2 a5 7e 25 eb 34 7c ff >>>>> OOB Data: 38 ea de 14 10 de 9b 40 33 16 6a cc 9d aa 2f 5e >>>>> >>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >>>>> --- >>>>> drivers/mtd/nand/raw/meson_nand.c | 5 +++++ >>>>> 1 file changed, 5 insertions(+) >>>>> >>>>> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c >>>>> index f84a10238e4d..f2f2472cb511 100644 >>>>> --- a/drivers/mtd/nand/raw/meson_nand.c >>>>> +++ b/drivers/mtd/nand/raw/meson_nand.c >>>>> @@ -858,9 +858,12 @@ static int meson_nfc_read_page_sub(struct nand_chip *nand, >>>>> static int meson_nfc_read_page_raw(struct nand_chip *nand, u8 *buf, >>>>> int oob_required, int page) >>>>> { >>>>> + struct mtd_info *mtd = nand_to_mtd(nand); >>>>> u8 *oob_buf = nand->oob_poi; >>>>> int ret; >>>>> >>>>> + memset(oob_buf, 0, mtd->oobsize); >>>> >>>> I'm surprised raw reads do not read the entire OOB? >>> >>> Yes! Seems in case of raw access (what i see in this driver) number of OOB bytes read >>> still depends on ECC parameters: for each portion of data covered with ECC code we can >>> read it's ECC code and "user bytes" from OOB - it is what i see by dumping DMA buffer by >>> printk(). For example I'm working with 2K NAND pages, each page has 2 x 1K ECC blocks. >>> For each ECC block I have 16 OOB bytes which I can access by read/write. Each 16 bytes >>> contains 2 bytes of user's data and 14 bytes ECC codes. So when I read page in raw mode >>> controller returns 32 bytes (2 x (2 + 14)) of OOB. While OOB is reported as 64 bytes. >> >> In all modes, when you read OOB, you should get the full OOB. The fact >> that ECC correction is enabled or disabled does not matter. If the NAND >> features OOB sections of 64 bytes, you should get the 64 bytes. >> >> What happens sometimes, is that some of the bytes are not protected >> against bitflips, but the policy is to return the full buffer. > > Ok, so to clarify case for this NAND controller: > 1) In both ECC and raw modes i need to return the same raw OOB data (e.g. user bytes > + ECC codes)? > 2) If I have access to only 32 bytes of OOB (in case above), I must report that size > of OOB is only 32 bytes during initialization? > > Thanks, Arseniy
Yes. it should return all the OOB data. i make a mistake on raw read and there is wrong code in meson_nfc_read_page_raw(). meson_nfc_get_data_oob(nand, buf, oob_buf); changed to: if (oob_required) memcpy(oob_buf, buf + mtd->writesize, mtd->oobsize)
for the ECC mode, i define the meson_ooblayout_ops in host driver.
> >> >>> >>> Thanks, Arseniy >>> >>>> >>>>> + >>>>> ret = meson_nfc_read_page_sub(nand, page, 1); >>>>> if (ret) >>>>> return ret; >>>>> @@ -881,6 +884,8 @@ static int meson_nfc_read_page_hwecc(struct nand_chip *nand, u8 *buf, >>>>> u8 *oob_buf = nand->oob_poi; >>>>> int ret, i; >>>>> >>>>> + memset(oob_buf, 0, mtd->oobsize); >>>>> + >>>>> ret = meson_nfc_read_page_sub(nand, page, 0); >>>>> if (ret) >>>>> return ret; >>>> >>>> >>>> Thanks, >>>> Miquèl >> >> >> Thanks, >> Miquèl >
-- Thanks, Liang
| |