1 files changed, 52 insertions, 4 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index b5c3768..4c2f39f 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1410,6 +1410,30 @@ static uint8_t *nand_transfer_oob(struct nand_chip *chip, uint8_t *oob,
 }
 
 /**
+ * nand_setup_read_retry - [INTERN] Set the READ RETRY mode
+ * @mtd: MTD device structure
+ * @retry_mode: the retry mode to use
+ *
+ * Some vendors supply a special command to shift the Vt threshold, to be used
+ * when there are too many bitflips in a page (i.e., ECC error). After setting
+ * a new threshold, the host should retry reading the page.
+ */
+static int nand_setup_read_retry(struct mtd_info *mtd, int retry_mode)
+{
+	struct nand_chip *chip = mtd->priv;
+
+	pr_debug("setting READ RETRY mode %d\n", retry_mode);
+
+	if (retry_mode >= chip->read_retries)
+		return -EINVAL;
+
+	if (!chip->setup_read_retry)
+		return -EOPNOTSUPP;
+
+	return chip->setup_read_retry(mtd, retry_mode);
+}
+
+/**
  * nand_do_read_ops - [INTERN] Read data with ECC
  * @mtd: MTD device structure
  * @from: offset to read from
@@ -1430,6 +1454,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 
 	uint8_t *bufpoi, *oob, *buf;
 	unsigned int max_bitflips = 0;
+	int retry_mode = 0;
 	bool ecc_fail = false;
 
 	chipnr = (int)(from >> chip->chip_shift);
@@ -1454,6 +1479,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 		if (realpage != chip->pagebuf || oob) {
 			bufpoi = aligned ? buf : chip->buffers->databuf;
 
+read_retry:
 			chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
 
 			/*
@@ -1494,8 +1520,6 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 				memcpy(buf, chip->buffers->databuf + col, bytes);
 			}
 
-			buf += bytes;
-
 			if (unlikely(oob)) {
 				int toread = min(oobreadlen, max_oobsize);
 
@@ -1514,8 +1538,24 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 					nand_wait_ready(mtd);
 			}
 
-			if (mtd->ecc_stats.failed - ecc_failures)
-				ecc_fail = true;
+			if (mtd->ecc_stats.failed - ecc_failures) {
+				if (retry_mode + 1 <= chip->read_retries) {
+					retry_mode++;
+					ret = nand_setup_read_retry(mtd,
+							retry_mode);
+					if (ret < 0)
+						break;
+
+					/* Reset failures; retry */
+					mtd->ecc_stats.failed = ecc_failures;
+					goto read_retry;
+				} else {
+					/* No more retry modes; real failure */
+					ecc_fail = true;
+				}
+			}
+
+			buf += bytes;
 		} else {
 			memcpy(buf, chip->buffers->databuf + col, bytes);
 			buf += bytes;
@@ -1525,6 +1565,14 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 
 		readlen -= bytes;
 
+		/* Reset to retry mode 0 */
+		if (retry_mode) {
+			ret = nand_setup_read_retry(mtd, 0);
+			if (ret < 0)
+				break;
+			retry_mode = 0;
+		}
+
 		if (!readlen)
 			break;