On 2017/12/07 0:08, Boris Brezillon wrote: > On Wed, 6 Dec 2017 23:04:57 +0900 > KOBAYASHI Yoshitake <[email protected]> wrote: > >> This patch enables support to read the ECC strength and size from the >> NAND flash using Toshiba Memory SLC NAND extended-ID. This patch is >> based on the information of the 6th ID byte of the Toshiba Memory SLC >> NAND. >> >> Signed-off-by: KOBAYASHI Yoshitake <[email protected]> >> --- >> drivers/mtd/nand/nand_toshiba.c | 28 ++++++++++++++++++++++++++++ >> 1 file changed, 28 insertions(+) >> >> diff --git a/drivers/mtd/nand/nand_toshiba.c >> b/drivers/mtd/nand/nand_toshiba.c >> index 57df857..c2c141b 100644 >> --- a/drivers/mtd/nand/nand_toshiba.c >> +++ b/drivers/mtd/nand/nand_toshiba.c >> @@ -35,6 +35,34 @@ static void toshiba_nand_decode_id(struct nand_chip *chip) >> (chip->id.data[5] & 0x7) == 0x6 /* 24nm */ && >> !(chip->id.data[4] & 0x80) /* !BENAND */) >> mtd->oobsize = 32 * mtd->writesize >> 9; >> + >> + /* >> + * Extract ECC requirements from 6th id byte. >> + * For Toshiba SLC, ecc requrements are as follows: >> + * - 43nm: 1 bit ECC for each 512Byte is required. >> + * - 32nm: 4 bit ECC for each 512Byte is required. >> + * - 24nm: 8 bit ECC for each 512Byte is required. >> + */ >> + if (chip->id.len >= 6 && nand_is_slc(chip)) { >> + chip->ecc_step_ds = 512; >> + switch (chip->id.data[5] & 0x7) { >> + case 0x4: >> + chip->ecc_strength_ds = 1; >> + break; >> + case 0x5: >> + chip->ecc_strength_ds = 4; >> + break; >> + case 0x6: >> + chip->ecc_strength_ds = 8; >> + break; >> + default: >> + WARN(1, "Could not get ECC info"); >> + chip->ecc_step_ds = 0; >> + break; >> + } >> + } else if (chip->id.len < 6 && nand_is_slc(chip)) { >> + WARN(1, "Could not get ECC info, 6th nand id byte does not >> exist."); > > I'm pretty sure you have old NAND chips that do not have 6bytes ids > (see the table here [1]), and printing a huge backtrace in this case is > probably not what you want. > > If you're okay with dropping this else block, I'll do the change when > applying, no need to send a new version.
Some controllers may have limitation in reading ids beyond 5 bytes, considering such scenario we think it is better to keep this warning. However if you feel huge backtrace is an issue, how about we using pr_warn() instead?
