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SubjectRe: [PATCH v4 5/7] mtd: rawnand: Support bad block markers in first, second or last page
Hi Schrempf,

Schrempf Frieder <frieder.schrempf@kontron.de> wrote on Mon, 18 Feb
2019 10:42:45 +0000:

> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>
> Currently supported bad block marker positions within the block are:
> * in first page only
> * in last page only
> * in first or second page
>
> Some ESMT NANDs are known to have been shipped by the manufacturer
> with bad block markers in the first or last page, instead of the
> first or second page.
>
> Also the datasheets for Cypress/Spansion/AMD NANDs claim that the
> first, second *and* last page needs to be checked.
>
> Therefore we make it possible to set NAND_BBM_FIRSTPAGE,
> NAND_BBM_SECONDPAGE and NAND_BBM_LASTPAGE independently in any
> combination.
>
> To simplify the code, the logic to evaluate the flags is moved to a
> a new function nand_bbm_get_next_page().
>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> Reviewed-by: Boris Brezillon <bbrezillon@kernel.org>
> ---
> drivers/mtd/nand/raw/internals.h | 1 +
> drivers/mtd/nand/raw/nand_base.c | 62 ++++++++++++++++++++++++-----------
> drivers/mtd/nand/raw/nand_bbt.c | 29 +++++++---------
> 3 files changed, 55 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/internals.h b/drivers/mtd/nand/raw/internals.h
> index fbf6ca015cd7..97ae67e009d5 100644
> --- a/drivers/mtd/nand/raw/internals.h
> +++ b/drivers/mtd/nand/raw/internals.h
> @@ -76,6 +76,7 @@ extern const struct nand_manufacturer_ops toshiba_nand_manuf_ops;
>
> /* Core functions */
> const struct nand_manufacturer *nand_get_manufacturer(u8 id);
> +int nand_bbm_get_next_page(struct nand_chip *chip, int page);
> int nand_markbad_bbm(struct nand_chip *chip, loff_t ofs);
> int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr,
> int allowbbt);
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 9ef7b86cdc42..7bc20c1fe23c 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -285,6 +285,31 @@ static void nand_release_device(struct nand_chip *chip)
> spin_unlock(&chip->controller->lock);
> }
>
> +/**
> + * nand_bbm_get_next_page - Get the next page for bad block markers
> + * @chip: NAND chip object
> + * @index: Current page, only pages beyond this will be considered

Why pages *beyond*? Can't you change the logic to use the page from
where to start searching? I am not sure such a change would be
clearer in the rest of the code but I don't like the tests against
"-1". Maybe you could just check negative values instead.

> + *
> + * Returns an integer that corresponds to the page offset within a block, for
> + * a page that is used to store bad block markers. If no more pages are
> + * available, -1 is returned.
> + */
> +int nand_bbm_get_next_page(struct nand_chip *chip, int page)
> +{
> + struct mtd_info *mtd = nand_to_mtd(chip);
> + int last_page = ((mtd->erasesize - mtd->writesize) >>
> + chip->page_shift) & chip->pagemask;
> +
> + if (page < 0 && chip->options & NAND_BBM_FIRSTPAGE)
> + return 0;
> + else if (page < 1 && chip->options & NAND_BBM_SECONDPAGE)
> + return 1;
> + else if (page < last_page && chip->options & NAND_BBM_LASTPAGE)
> + return last_page;
> +
> + return -1;

I would prefer a named value (like -EINVAL) and checks against a
negative value (not -1).

> +}
> +
> /**
> * nand_block_bad - [DEFAULT] Read bad block marker from the chip
> * @chip: NAND chip object
> @@ -294,19 +319,14 @@ static void nand_release_device(struct nand_chip *chip)
> */
> static int nand_block_bad(struct nand_chip *chip, loff_t ofs)
> {
> - struct mtd_info *mtd = nand_to_mtd(chip);
> - int page, page_end, res;
> + int page_offset;
> + int res, first_page = (int)(ofs >> chip->page_shift) & chip->pagemask;

Maybe:

int first_page, page_offset;
int res;
u8 bad;

first_page = (int)(ofs >> chip->page_shift) & chip->pagemask;
page_offset = nand_bbm_get_next_page(chip, -1);

> u8 bad;
>
> - if (chip->options & NAND_BBM_LASTPAGE)
> - ofs += mtd->erasesize - mtd->writesize;
> + page_offset = nand_bbm_get_next_page(chip, -1);
>
> - page = (int)(ofs >> chip->page_shift) & chip->pagemask;
> - page_end = page + (((chip->options & NAND_BBM_FIRSTPAGE) &&
> - (chip->options & NAND_BBM_SECONDPAGE)) ? 2 : 1);
> -
> - for (; page < page_end; page++) {
> - res = chip->ecc.read_oob(chip, page);
> + while (page_offset != -1) {
> + res = chip->ecc.read_oob(chip, first_page + page_offset);
> if (res < 0)
> return res;
>
> @@ -318,6 +338,8 @@ static int nand_block_bad(struct nand_chip *chip, loff_t ofs)
> res = hweight8(bad) < chip->badblockbits;
> if (res)
> return res;
> +
> + page_offset = nand_bbm_get_next_page(chip, page_offset);
> }
>
> return 0;
> @@ -528,7 +550,7 @@ static int nand_default_block_markbad(struct nand_chip *chip, loff_t ofs)
> struct mtd_info *mtd = nand_to_mtd(chip);
> struct mtd_oob_ops ops;
> uint8_t buf[2] = { 0, 0 };
> - int ret = 0, res, i = 0;
> + int ret = 0, res, page_offset;
>
> memset(&ops, 0, sizeof(ops));
> ops.oobbuf = buf;
> @@ -541,18 +563,18 @@ static int nand_default_block_markbad(struct nand_chip *chip, loff_t ofs)
> }
> ops.mode = MTD_OPS_PLACE_OOB;
>
> - /* Write to first/last page(s) if necessary */
> - if (chip->options & NAND_BBM_LASTPAGE)
> - ofs += mtd->erasesize - mtd->writesize;
> - do {
> - res = nand_do_write_oob(chip, ofs, &ops);
> + page_offset = nand_bbm_get_next_page(chip, -1);
> +
> + while (page_offset != -1) {
> + res = nand_do_write_oob(chip,
> + ofs + page_offset * mtd->writesize,
> + &ops);
> +
> if (!ret)
> ret = res;
>
> - i++;
> - ofs += mtd->writesize;
> - } while ((chip->options & NAND_BBM_FIRSTPAGE) &&
> - (chip->options & NAND_BBM_SECONDPAGE) && i < 2);
> + page_offset = nand_bbm_get_next_page(chip, page_offset);
> + }
>
> return ret;
> }
> diff --git a/drivers/mtd/nand/raw/nand_bbt.c b/drivers/mtd/nand/raw/nand_bbt.c
> index 7463afddc7ac..09603c502931 100644
> --- a/drivers/mtd/nand/raw/nand_bbt.c
> +++ b/drivers/mtd/nand/raw/nand_bbt.c
> @@ -415,11 +415,12 @@ static void read_abs_bbts(struct nand_chip *this, uint8_t *buf,
>
> /* Scan a given block partially */
> static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
> - loff_t offs, uint8_t *buf, int numpages)
> + loff_t offs, uint8_t *buf)
> {
> struct mtd_info *mtd = nand_to_mtd(this);
> +
> struct mtd_oob_ops ops;
> - int j, ret;
> + int ret, page_offset;
>
> ops.ooblen = mtd->oobsize;
> ops.oobbuf = buf;
> @@ -427,12 +428,15 @@ static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
> ops.datbuf = NULL;
> ops.mode = MTD_OPS_PLACE_OOB;
>
> - for (j = 0; j < numpages; j++) {
> + page_offset = nand_bbm_get_next_page(this, -1);
> +
> + while (page_offset != -1) {
> /*
> * Read the full oob until read_oob is fixed to handle single
> * byte reads for 16 bit buswidth.
> */
> - ret = mtd_read_oob(mtd, offs, &ops);
> + ret = mtd_read_oob(mtd, offs + page_offset * mtd->writesize,

Can you add '(' & ')' please?

> + &ops);
> /* Ignore ECC errors when checking for BBM */
> if (ret && !mtd_is_bitflip_or_eccerr(ret))
> return ret;
> @@ -440,8 +444,9 @@ static int scan_block_fast(struct nand_chip *this, struct nand_bbt_descr *bd,
> if (check_short_pattern(buf, bd))
> return 1;
>
> - offs += mtd->writesize;
> + page_offset = nand_bbm_get_next_page(this, page_offset);
> }
> +
> return 0;
> }
>
> @@ -460,18 +465,11 @@ static int create_bbt(struct nand_chip *this, uint8_t *buf,
> struct nand_bbt_descr *bd, int chip)
> {
> struct mtd_info *mtd = nand_to_mtd(this);
> - int i, numblocks, numpages;
> - int startblock;
> + int i, numblocks, startblock;
> loff_t from;
>
> pr_info("Scanning device for bad blocks\n");
>
> - if ((this->options & NAND_BBM_FIRSTPAGE) &&
> - (this->options & NAND_BBM_SECONDPAGE))
> - numpages = 2;
> - else
> - numpages = 1;
> -
> if (chip == -1) {
> numblocks = mtd->size >> this->bbt_erase_shift;
> startblock = 0;
> @@ -488,15 +486,12 @@ static int create_bbt(struct nand_chip *this, uint8_t *buf,
> from = (loff_t)startblock << this->bbt_erase_shift;
> }
>
> - if (this->options & NAND_BBM_LASTPAGE)
> - from += mtd->erasesize - (mtd->writesize * numpages);
> -
> for (i = startblock; i < numblocks; i++) {
> int ret;
>
> BUG_ON(bd->options & NAND_BBT_NO_OOB);
>
> - ret = scan_block_fast(this, bd, from, buf, numpages);
> + ret = scan_block_fast(this, bd, from, buf);
> if (ret < 0)
> return ret;
>




Thanks,
Miquèl

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