Re: [PATCH 2/2] mtd: spi-nand: Add read retry support

Miquel Raynal
2024-10-01T10:17:26Z

Hi Cheng Ming,

linchengming884@gmail.com wrote on Thu, 5 Sep 2024 13:53:33 +0800:

> From: Cheng Ming Lin <chengminglin@mxic.com.tw>
>
> When the host ECC fails to correct the data error of NAND device,
> there's a special read for data recovery method which host setups
> for the next read retry mode and may recover the lost data by host
> ECC again.
>
> Signed-off-by: Cheng Ming Lin <chengminglin@mxic.com.tw>
> ---
> drivers/mtd/nand/spi/core.c | 33 +++++++++++++++++++++++++++++++--
> 1 file changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index e0b6715e5dfe..2f21ea926132 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -640,6 +640,7 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
> struct nand_io_iter iter;
> bool disable_ecc = false;
> bool ecc_failed = false;
> + u8 retry_mode = 0;
> int ret = 0;
>
> if (ops->mode == MTD_OPS_RAW || !spinand->eccinfo.ooblayout)
> @@ -657,20 +658,45 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,

This will no longer apply with continuous support added in. However
please make this only in the non continuous path. I don't think it can
fly in the other.

> if (ret)
> break;
>
> +read_retry:
> ret = spinand_read_page(spinand, &iter.req);
> if (ret < 0 && ret != -EBADMSG)
> break;
>
> - if (ret == -EBADMSG)
> + if (ret == -EBADMSG && spinand->info->fixups) {
> + if (spinand->read_retries && ((retry_mode + 1) < spinand->read_retries)) {

++retry_mode?
> + retry_mode++;

So this can be dropped.

> + ret = spinand->info->fixups->setup_read_retry(spinand, retry_mode);
> + if (ret < 0)
> + break;

No, you need to set ecc_failed here.

> +
> + /* Reset ecc_stats; retry */
> + mtd->ecc_stats = old_stats;
> + goto read_retry;
> + } else {
> + /* No more retry modes; real failure */
> + ecc_failed = true;
> + }
> + } else if (ret == -EBADMSG) {
> ecc_failed = true;
> - else
> + } else {
> max_bitflips = max_t(unsigned int, max_bitflips, ret);
> + }
>
> ret = 0;
> ops->retlen += iter.req.datalen;
> ops->oobretlen += iter.req.ooblen;
> +
> + /* Reset to retry mode 0*/
> + if (retry_mode) {

retry_mode = 0;

> + ret = spinand->info->fixups->setup_read_retry(spinand, 0);

retry_mode);

> + if (ret < 0)
> + break;

this if clause is useless.

> + retry_mode = 0;

And then this can be dropped from here.

> + }
> }
>
> +

Spurious line

> if (ops->stats) {
> ops->stats->uncorrectable_errors +=
> mtd->ecc_stats.failed - old_stats.failed;
> @@ -1095,6 +1121,9 @@ int spinand_match_and_init(struct spinand_device *spinand,
> spinand->flags = table[i].flags;
> spinand->id.len = 1 + table[i].devid.len;
> spinand->select_target = table[i].select_target;
> + spinand->info = info;
> + if (spinand->info->fixups && spinand->info->fixups->init_read_retry)
> + spinand->read_retries = spinand->info->fixups->init_read_retry(spinand);

Now I get you init. Ok, fine.

>
> op = spinand_select_op_variant(spinand,
> info->op_variants.read_cache);

Thanks,
Miquèl