Messages in this thread | | | Date | Fri, 15 Oct 2021 10:38:00 +0100 | From | Paul Cercueil <> | Subject | Re: [PATCH 2/3] mtd: rawnand: Export nand_read_page_hwecc_oob_first() |
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Hi,
Le ven., oct. 15 2021 at 11:35:15 +0200, Miquel Raynal <miquel.raynal@bootlin.com> a écrit : > Hi Paul, > >> >> */ >> >> >> >> /* An ECC layout for using 4-bit ECC with small-page >> flash, >> storing >> >> >> @@ -648,7 +580,7 @@ static int >> davinci_nand_attach_chip(struct >> >> nand_chip *chip) >> >> >> } else if (chunks == 4 || chunks == 8) { >> >> >> mtd_set_ooblayout(mtd, >> >> >> nand_get_large_page_ooblayout()); >> >> >> - chip->ecc.read_page = >> >> nand_davinci_read_page_hwecc_oob_first; >> >> >> + chip->ecc.read_page = nand_read_page_hwecc_oob_first; >> >> >> } else { >> >> >> return -EIO; >> >> >> } >> >> >> diff --git a/drivers/mtd/nand/raw/nand_base.c >> >> >> b/drivers/mtd/nand/raw/nand_base.c >> >> >> index 3d6c6e880520..cb5f343b9fa2 100644 >> >> >> --- a/drivers/mtd/nand/raw/nand_base.c >> >> >> +++ b/drivers/mtd/nand/raw/nand_base.c >> >> >> @@ -3160,6 +3160,75 @@ static int >> nand_read_page_hwecc(struct >> >> nand_chip *chip, uint8_t *buf, >> >> >> return max_bitflips; >> >> >> } >> >> >> >> +/** >> >> >> + * nand_read_page_hwecc_oob_first - Hardware ECC page read >> >> with ECC >> >> >> + * data read from OOB area >> >> >> + * @chip: nand chip info structure >> >> >> + * @buf: buffer to store read data >> >> >> + * @oob_required: caller requires OOB data read to >> >> chip->oob_poi >> >> >> + * @page: page number to read >> >> >> + * >> >> >> + * Hardware ECC for large page chips, require OOB to be >> read >> >> first. For this >> >> > >> >> > requires >> >> > >> >> > With this ECC configuration? >> >> > >> >> >> + * ECC mode, the write_page method is re-used from ECC_HW. >> >> These >> methods >> >> > >> >> > I do not understand this sentence nor the next one about >> >> syndrome. I >> >> > believe it is related to your engine and should not leak into >> the >> > core. >> >> > >> >> >> + * read/write ECC from the OOB area, unlike the >> >> ECC_HW_SYNDROME >> support with >> >> >> + * multiple ECC steps, follows the "infix ECC" scheme and >> >> >> reads/writes ECC from >> >> >> + * the data area, by overwriting the NAND manufacturer bad >> >> block >> markings. >> >> > >> >> > That's a sentence I don't like. What do you mean exactly? >> >> > >> >> > What "Infix ECC" scheme is? >> >> > >> >> > Do you mean that unlike the syndrome mode it *does not* >> >> overwrite the >> >> > BBM ? >> >> >> I don't mean anything. I did not write that comment. I just >> moved >> the function verbatim with no changes. If something needs >> to be >> fixed, then it needs to be fixed before/after this patch. >> > >> > Well, this comment should be adapted because as-is I don't think >> it's >> > wise to move it around. >> >> OK. >> >> I think it says that BBM can be overwritten with this >> configuration, but that would be if the OOB layout covers the BBM >> area. > > If the ooblayout prevents the BBM to be smatched I'm fine and this > sentence should disappear because it's misleading. > >> >> >> >> + */ >> >> >> +int nand_read_page_hwecc_oob_first(struct nand_chip *chip, >> >> uint8_t >> *buf, >> >> >> + int oob_required, int page) >> >> >> +{ >> >> >> + struct mtd_info *mtd = nand_to_mtd(chip); >> >> >> + int i, eccsize = chip->ecc.size, ret; >> >> >> + int eccbytes = chip->ecc.bytes; >> >> >> + int eccsteps = chip->ecc.steps; >> >> >> + uint8_t *p = buf; >> >> >> + uint8_t *ecc_code = chip->ecc.code_buf; >> >> >> + unsigned int max_bitflips = 0; >> >> >> + >> >> >> + /* Read the OOB area first */ >> >> >> + ret = nand_read_oob_op(chip, page, 0, chip->oob_poi, >> >> >> mtd->oobsize); >> >> >> + if (ret) >> >> >> + return ret; >> >> >> + >> >> >> + ret = nand_read_page_op(chip, page, 0, NULL, 0); >> >> > >> >> > Definitely not, your are requesting the chip to do the >> read_page >> >> > operation twice. You only need a nand_change_read_column I >> >> believe. >> >> >> Again, this code is just being moved around - don't shoot >> the >> messenger :) >> > >> > haha >> > >> > Well, now you touch the core, so I need to be more careful, and >> the >> > code is definitely wrong, so even if we don't move that code off, >> you >> > definitely want to fix it in order to improve your performances. >> >> I don't see the read_page being done twice? >> >> There's one read_oob, one read_page, then read_data in the loop. > > read_oob and read_page both end up sending READ0 and READSTART so > they do request the chip to perform an internal read twice. You > need this only once. The call to nand_read_page_op() should be a > nand_change_read_column() with no data requested.
OK.
> >> >> >> /** >> >> >> * nand_read_page_syndrome - [REPLACEABLE] hardware ECC >> >> syndrome >> based page read >> >> >> * @chip: nand chip info structure >> >> >> diff --git a/include/linux/mtd/rawnand.h >> >> >> b/include/linux/mtd/rawnand.h >> >> >> index b2f9dd3cbd69..5b88cd51fadb 100644 >> >> >> --- a/include/linux/mtd/rawnand.h >> >> >> +++ b/include/linux/mtd/rawnand.h >> >> >> @@ -1539,6 +1539,8 @@ int nand_read_data_op(struct >> nand_chip >> *chip, >> void *buf, unsigned int len, >> >> >> bool force_8bit, bool check_only); >> >> >> int nand_write_data_op(struct nand_chip *chip, const void >> *buf, >> >> >> unsigned int len, bool force_8bit); >> >> >> +int nand_read_page_hwecc_oob_first(struct nand_chip *chip, >> >> uint8_t >> *buf, >> >> >> + int oob_required, int page); >> >> > >> >> > You certainly want to add this symbol closer to the other >> >> read/write >> >> > page helpers? >> >> >> Where would that be? The other read/write page helpers are >> all >> "static" so they don't appear in any header. >> > >> > I believe we should keep this header local as long as there are no >> > other users. >> >> I'll move it to internal.h then. > > Why do you want to put it there is there is only one user?
But there are two users: davinci_nand.c and (with patch [3/3]) ingenic/ingenic_nand_drv.c.
-Paul
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