On Fri, 11 May 2018 14:44:07 +0200
Boris Brezillon <boris.brezillon@xxxxxxxxxxx> wrote:
> The ONFI spec clearly says that FAIL bit is only valid for PROGRAM,
> ERASE and READ-with-on-die-ECC operations, and should be ignored
> otherwise.
>
> It seems that checking it after sending a SET_FEATURES is a bad idea
> because a previous READ, PROGRAM or ERASE op may have failed, and
> depending on the implementation, the FAIL bit is not cleared until a
> new READ, PROGRAM or ERASE is started.
>
> This leads to ->set_features() returning -EIO while it actually worked,
> which can sometimes stop a batch of READ/PROGRAM ops.
>
> Note that we only fix the ->exec_op() path here, because some drivers
> are abusing the NAND_STATUS_FAIL flag in their ->waitfunc()
> implementation to propagate other kind of errors, like
> wait-ready-timeout or controller-related errors. Let's not try to fix
> those drivers since they worked fine so far.
>
> Fixes: 8878b126df76 ("mtd: nand: add ->exec_op() implementation")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
Applied to nand/next.
> ---
> This patch is fixing a problem we had with on-die ECC on Micron
> NANDs [1].
> On these chips, when you have an ECC failure, the FAIL bit is set and
> it's not cleared until the next READ operation, which led the following
> SET_FEATURES (used to re-enable on-die ECC) to fail with -EIO and
> stopped the batch of page reads started by UBIFS, which in turn led to
> unmountable FS.
>
> [1]http://patchwork.ozlabs.org/patch/907874/
>
> Changes in v2:
> - Fix the subject prefix
> ---
> drivers/mtd/nand/raw/nand_base.c | 27 +++++++++------------------
> 1 file changed, 9 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index f28c3a555861..ee29f34562ab 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -2174,7 +2174,6 @@ static int nand_set_features_op(struct nand_chip *chip, u8 feature,
> struct mtd_info *mtd = nand_to_mtd(chip);
> const u8 *params = data;
> int i, ret;
> - u8 status;
>
> if (chip->exec_op) {
> const struct nand_sdr_timings *sdr =
> @@ -2188,26 +2187,18 @@ static int nand_set_features_op(struct nand_chip *chip, u8 feature,
> };
> struct nand_operation op = NAND_OPERATION(instrs);
>
> - ret = nand_exec_op(chip, &op);
> - if (ret)
> - return ret;
> -
> - ret = nand_status_op(chip, &status);
> - if (ret)
> - return ret;
> - } else {
> - chip->cmdfunc(mtd, NAND_CMD_SET_FEATURES, feature, -1);
> - for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
> - chip->write_byte(mtd, params[i]);
> + return nand_exec_op(chip, &op);
> + }
>
> - ret = chip->waitfunc(mtd, chip);
> - if (ret < 0)
> - return ret;
> + chip->cmdfunc(mtd, NAND_CMD_SET_FEATURES, feature, -1);
> + for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
> + chip->write_byte(mtd, params[i]);
>
> - status = ret;
> - }
> + ret = chip->waitfunc(mtd, chip);
> + if (ret < 0)
> + return ret;
>
> - if (status & NAND_STATUS_FAIL)
> + if (ret & NAND_STATUS_FAIL)
> return -EIO;
>
> return 0;
