Messages in this thread | | | Date | Wed, 12 Apr 2023 12:20:55 +0300 | Subject | Re: [PATCH v1 4/5] mtd: rawnand: meson: clear OOB buffer before read | From | Arseniy Krasnov <> |
| |
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.
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
| |