On Thu, 21 Jun 2018 22:33:27 +1200 Chris Packham <[email protected]> wrote:
> Micron MT29F1G08ABAFAWP-ITE:F supports an on-die ECC with 8 bits > per 512 bytes. Add support for this combination. > > Signed-off-by: Chris Packham <[email protected]> > --- > Changes in v2: > - New > Changes in v3: > - Handle reporting of corrected errors that don't require a rewrite, expand > comment for the ECC status bits. > Changes in v4: > - Use a switch statement for handling ECC status > - Update ecc_stats.corrected > > drivers/mtd/nand/raw/nand_micron.c | 68 ++++++++++++++++++++---------- > 1 file changed, 46 insertions(+), 22 deletions(-) > > diff --git a/drivers/mtd/nand/raw/nand_micron.c > b/drivers/mtd/nand/raw/nand_micron.c > index d30bd4df9b12..f1ecd4986b50 100644 > --- a/drivers/mtd/nand/raw/nand_micron.c > +++ b/drivers/mtd/nand/raw/nand_micron.c > @@ -18,10 +18,28 @@ > #include <linux/mtd/rawnand.h> > > /* > - * Special Micron status bit that indicates when the block has been > - * corrected by on-die ECC and should be rewritten > + * Special Micron status bit 3 indicates that the block has been > + * corrected by on-die ECC and should be rewritten. > + * > + * On chips with 8-bit ECC and additional bit can be used to distinguish > + * cases where a errors were corrected without needing a rewrite > + * > + * Bit 4 Bit 3 Bit 0 Description > + * ----- ----- ----- ----------- > + * 0 0 0 No Errors > + * 0 0 1 Multiple uncorrected errors > + * 0 1 0 4 - 6 errors corrected, recommend rewrite > + * 0 1 1 Reserved > + * 1 0 0 1 - 3 errors corrected > + * 1 0 1 Reserved > + * 1 1 0 7 - 8 errors corrected, recommend rewrite > */ > -#define NAND_STATUS_WRITE_RECOMMENDED BIT(3) > +#define NAND_STATUS_MASK (BIT(4) | BIT(3) | BIT(0)) > +#define NAND_STATUS_NO_ERRORS 0 > +#define NAND_STATUS_UNCORRECTABLE BIT(0) > +#define NAND_STATUS_4_6_CORRECTED BIT(3) > +#define NAND_STATUS_1_3_CORRECTED BIT(4) > +#define NAND_STATUS_7_8_CORRECTED (BIT(4) | BIT(3)) NAND_ECC_STATUS_ prefix would be better than NAND_STATUS_ > > struct nand_onfi_vendor_micron { > u8 two_plane_read; > @@ -137,18 +155,31 @@ micron_nand_read_page_on_die_ecc(struct mtd_info *mtd, > struct nand_chip *chip, > if (ret) > goto out; > > - if (status & NAND_STATUS_FAIL) { > + /* > + * The internal ECC doesn't tell us the number of bitflips > + * that have been corrected, but tells us if it recommends to > + * rewrite the block. If it's the case, then we pretend we had > + * a number of bitflips equal to the ECC strength, which will > + * hint the NAND core to rewrite the block. > + */ > + switch (status & NAND_STATUS_MASK) { > + case NAND_STATUS_UNCORRECTABLE: I'd recommend handling 8bit and 4bit on-die ECC separately (create on subfunction per kind of ECC), and not using the same _MASK, just in case unused bits value have a different meaning or are simply not set to 0 by default. > mtd->ecc_stats.failed++; > - } else if (status & NAND_STATUS_WRITE_RECOMMENDED) { > - /* > - * The internal ECC doesn't tell us the number of bitflips > - * that have been corrected, but tells us if it recommends to > - * rewrite the block. If it's the case, then we pretend we had > - * a number of bitflips equal to the ECC strength, which will > - * hint the NAND core to rewrite the block. > - */ > - mtd->ecc_stats.corrected += chip->ecc.strength; > + break; > + case NAND_STATUS_1_3_CORRECTED: > + mtd->ecc_stats.corrected++; > + max_bitflips = 1; Should you always take the max of the range, so here: mtd->ecc_stats.corrected += 3; max_bitflips = 3; > + break; > + case NAND_STATUS_4_6_CORRECTED: > + mtd->ecc_stats.corrected += 4; += 6; > + /* rewrite recommended */ > + max_bitflips = chip->ecc.strength; Here it should be 6, not chip->ecc.strength. > + break; > + case NAND_STATUS_7_8_CORRECTED: > + mtd->ecc_stats.corrected += 7; += 8; > + /* rewrite recommended */ > max_bitflips = chip->ecc.strength; > + break; > } > > ret = nand_read_data_op(chip, buf, mtd->writesize, false); > @@ -239,13 +270,6 @@ static int micron_supports_on_die_ecc(struct nand_chip > *chip) > if (feature[0] & ONFI_FEATURE_ON_DIE_ECC_EN) > return MICRON_ON_DIE_MANDATORY; > > - /* > - * Some Micron NANDs have an on-die ECC of 4/512, some other > - * 8/512. We only support the former. > - */ > - if (chip->ecc_strength_ds != 4) > - return MICRON_ON_DIE_UNSUPPORTED; I'd prefer to keep an explicit check here rather than accepting everything. See how 8 and 4 bit ECC differ, it's likely to be the case if Micron ever has a 16bit ECC. > - > return MICRON_ON_DIE_SUPPORTED; > } > > @@ -275,9 +299,9 @@ static int micron_nand_init(struct nand_chip *chip) > return -EINVAL; > } > > - chip->ecc.bytes = 8; > + chip->ecc.bytes = chip->ecc_strength_ds * 2; > chip->ecc.size = 512; > - chip->ecc.strength = 4; > + chip->ecc.strength = chip->ecc_strength_ds; > chip->ecc.algo = NAND_ECC_BCH; > chip->ecc.read_page = micron_nand_read_page_on_die_ecc; > chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
