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

Cheng Ming Lin
2024-09-05T05:55:47Z

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

+
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);

op = spinand_select_op_variant(spinand,
info->op_variants.read_cache);
--
2.25.1