[PATCH] mtd: nand: use .read_oob() instead of .cmdfunc() for bad block check

Masahiro Yamada
2017-03-14T17:47:05Z

The nand_default_block_markbad() is the default implementation of
chip->block_markbad(). This is called for marking a block as bad.
It invokes nand_do_write_oob(), then calls a higher level accessor
ecc->write_oob().

On the other hand, when reading BBM from the OOB, chip->block_bad()
is called, and nand_block_bad() is the default implementation. This
function calls a lower level chip->cmdfunc(). If a driver wants to
re-use nand_block_bad(), it is required to support NAND_CMD_READOOB
in its cmdfunc(). This is strange. If the controller supports
optimized read operation and the driver has its own ecc->read_oob(),
it should be able to use it. Besides, NAND_CMD_READOOB (0x50) is
not a real command for large page devices. So, recent drivers may
not be happy to handle this command.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

At first, I tried to call nand_do_read_oob() from nand_block_bad()
in order to make to make things symmetry, but it did not work.
chip->select_chip() is handled outside of nand_block_bad(), so
nand_do_read_oob() can not be used there.

drivers/mtd/nand/nand_base.c | 38 +++++++++++++++++---------------------
1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index a3c0f47..78c5cd6 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -354,9 +354,9 @@ static void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
*/
static int nand_block_bad(struct mtd_info *mtd, loff_t ofs)
{
- int page, res = 0, i = 0;
+ int page, res = 0, ret = 0, i = 0;
struct nand_chip *chip = mtd_to_nand(mtd);
- u16 bad;
+ u8 bad;

if (chip->bbt_options & NAND_BBT_SCANLASTPAGE)
ofs += mtd->erasesize - mtd->writesize;
@@ -364,30 +364,26 @@ static int nand_block_bad(struct mtd_info *mtd, loff_t ofs)
page = (int)(ofs >> chip->page_shift) & chip->pagemask;

do {
- if (chip->options & NAND_BUSWIDTH_16) {
- chip->cmdfunc(mtd, NAND_CMD_READOOB,
- chip->badblockpos & 0xFE, page);
- bad = cpu_to_le16(chip->read_word(mtd));
- if (chip->badblockpos & 0x1)
- bad >>= 8;
+ res = chip->ecc.read_oob(mtd, chip, page);
+ if (!res) {
+ bad = chip->oob_poi[chip->badblockpos];
+
+ if (likely(chip->badblockbits == 8))
+ res = bad != 0xFF;
else
- bad &= 0xFF;
- } else {
- chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos,
- page);
- bad = chip->read_byte(mtd);
+ res = hweight8(bad) < chip->badblockbits;
+ if (res)
+ return res;
}

- if (likely(chip->badblockbits == 8))
- res = bad != 0xFF;
- else
- res = hweight8(bad) < chip->badblockbits;
- ofs += mtd->writesize;
- page = (int)(ofs >> chip->page_shift) & chip->pagemask;
+ if (!ret)
+ ret = res;
+
+ page++;
i++;
- } while (!res && i < 2 && (chip->bbt_options & NAND_BBT_SCAN2NDPAGE));
+ } while (chip->bbt_options & NAND_BBT_SCAN2NDPAGE && i < 2);

- return res;
+ return ret;
}

/**
--
2.7.4