Re: [PATCH 2/3] mtd: rawnand: Export nand_read_page_hwecc_oob_first()

Paul Cercueil
2021-10-15T08:38:46Z

Hi Miquel,

Le ven., oct. 15 2021 at 08:13:13 +0200, Miquel Raynal
<miquel.raynal@bootlin.com> a écrit :
> Hi Paul,
>
> paul@crapouillou.net wrote on Sat, 9 Oct 2021 20:49:51 +0200:
>
>> Move the function nand_read_page_hwecc_oob_first() (previously
>> nand_davinci_read_page_hwecc_oob_first()) to nand_base.c, and
>> export it
>> as a GPL symbol, so that it can be used by more modules.
>>
>> Cc: <stable@vger.kernel.org> # v5.2
>> Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the
>> JZ4740")
>> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
>> ---
>> drivers/mtd/nand/raw/davinci_nand.c | 70
>> +----------------------------
>> drivers/mtd/nand/raw/nand_base.c | 69
>> ++++++++++++++++++++++++++++
>> include/linux/mtd/rawnand.h | 2 +
>> 3 files changed, 72 insertions(+), 69 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/raw/davinci_nand.c
>> b/drivers/mtd/nand/raw/davinci_nand.c
>> index 89de24d3bb7a..45fec8c192ab 100644
>> --- a/drivers/mtd/nand/raw/davinci_nand.c
>> +++ b/drivers/mtd/nand/raw/davinci_nand.c
>> @@ -371,74 +371,6 @@ static int nand_davinci_correct_4bit(struct
>> nand_chip *chip, u_char *data,
>> return corrected;
>> }
>>
>> -/**
>> - * nand_read_page_hwecc_oob_first - hw ecc, read oob first
>> - * @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
>> - * ECC mode, the write_page method is re-used from ECC_HW. These
>> methods
>> - * 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.
>> - */
>> -static int nand_davinci_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);
>> - if (ret)
>> - return ret;
>> -
>> - ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
>> - chip->ecc.total);
>> - if (ret)
>> - return ret;
>> -
>> - for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
>> - int stat;
>> -
>> - chip->ecc.hwctl(chip, NAND_ECC_READ);
>> -
>> - ret = nand_read_data_op(chip, p, eccsize, false, false);
>> - if (ret)
>> - return ret;
>> -
>> - stat = chip->ecc.correct(chip, p, &ecc_code[i], NULL);
>> - if (stat == -EBADMSG &&
>> - (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
>> - /* check for empty pages with bitflips */
>> - stat = nand_check_erased_ecc_chunk(p, eccsize,
>> - &ecc_code[i],
>> - eccbytes, NULL, 0,
>> - chip->ecc.strength);
>> - }
>> -
>> - if (stat < 0) {
>> - mtd->ecc_stats.failed++;
>> - } else {
>> - mtd->ecc_stats.corrected += stat;
>> - max_bitflips = max_t(unsigned int, max_bitflips, stat);
>> - }
>> - }
>> - return max_bitflips;
>> -}
>> -
>>
>> /*----------------------------------------------------------------------*/
>>
>> /* 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.

>> + */
>> +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
:)

>> + if (ret)
>> + return ret;
>> +
>> + ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
>> + chip->ecc.total);
>> + if (ret)
>> + return ret;
>> +
>> + for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
>> + int stat;
>> +
>> + chip->ecc.hwctl(chip, NAND_ECC_READ);
>> +
>> + ret = nand_read_data_op(chip, p, eccsize, false, false);
>> + if (ret)
>> + return ret;
>> +
>> + stat = chip->ecc.correct(chip, p, &ecc_code[i], NULL);
>> + if (stat == -EBADMSG &&
>> + (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
>> + /* check for empty pages with bitflips */
>> + stat = nand_check_erased_ecc_chunk(p, eccsize,
>> + &ecc_code[i],
>> + eccbytes, NULL, 0,
>> + chip->ecc.strength);
>> + }
>> +
>> + if (stat < 0) {
>> + mtd->ecc_stats.failed++;
>> + } else {
>> + mtd->ecc_stats.corrected += stat;
>> + max_bitflips = max_t(unsigned int, max_bitflips, stat);
>> + }
>> + }
>> + return max_bitflips;
>> +}
>> +EXPORT_SYMBOL_GPL(nand_read_page_hwecc_oob_first);
>> +
>> /**
>> * 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.

Cheers,
-Paul

>>
>> /* Scan and identify a NAND device */
>> int nand_scan_with_ids(struct nand_chip *chip, unsigned int
>> max_chips,
>
>
> Thanks,
> Miquèl