4 files changed, 35 insertions, 12 deletions

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 49c0814..deda5f2 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -217,11 +217,23 @@ int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
 	     u_char *buf)
 {
+	int ret_code;
 	if (from < 0 || from > mtd->size || len > mtd->size - from)
 		return -EINVAL;
 	if (!len)
 		return 0;
-	return mtd->_read(mtd, from, len, retlen, buf);
+
+	/*
+	 * In the absence of an error, drivers return a non-negative integer
+	 * representing the maximum number of bitflips that were corrected on
+	 * any one ecc region (if applicable; zero otherwise).
+	 */
+	ret_code = mtd->_read(mtd, from, len, retlen, buf);
+	if (unlikely(ret_code < 0))
+		return ret_code;
+	if (mtd->ecc_strength == 0)
+		return 0;	/* device lacks ecc */
+	return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;
 }
 
 int mtd_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 9dfe7bb..146ce11 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -53,12 +53,12 @@ static int part_read(struct mtd_info *mtd, loff_t from, size_t len,
 
 	stats = part->master->ecc_stats;
 	res = mtd_read(part->master, from + part->offset, len, retlen, buf);
-	if (unlikely(res)) {
-		if (mtd_is_bitflip(res))
-			mtd->ecc_stats.corrected += part->master->ecc_stats.corrected - stats.corrected;
-		if (mtd_is_eccerr(res))
-			mtd->ecc_stats.failed += part->master->ecc_stats.failed - stats.failed;
-	}
+	if (unlikely(mtd_is_eccerr(res)))
+		mtd->ecc_stats.failed +=
+			part->master->ecc_stats.failed - stats.failed;
+	else
+		mtd->ecc_stats.corrected +=
+			part->master->ecc_stats.corrected - stats.corrected;
 	return res;
 }
 
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 9e05cef..d4d586c 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1238,6 +1238,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 		mtd->oobavail : mtd->oobsize;
 
 	uint8_t *bufpoi, *oob, *buf;
+	unsigned int max_bitflips = 0;
 
 	stats = mtd->ecc_stats;
 
@@ -1265,7 +1266,10 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 
 			chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
 
-			/* Now read the page into the buffer */
+			/*
+			 * Now read the page into the buffer.  Absent an error,
+			 * the read methods return max bitflips per ecc step.
+			 */
 			if (unlikely(ops->mode == MTD_OPS_RAW))
 				ret = chip->ecc.read_page_raw(mtd, chip, bufpoi,
 							      oob_required,
@@ -1284,15 +1288,19 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 				break;
 			}
 
+			max_bitflips = max_t(unsigned int, max_bitflips, ret);
+
 			/* Transfer not aligned data */
 			if (!aligned) {
 				if (!NAND_HAS_SUBPAGE_READ(chip) && !oob &&
 				    !(mtd->ecc_stats.failed - stats.failed) &&
-				    (ops->mode != MTD_OPS_RAW))
+				    (ops->mode != MTD_OPS_RAW)) {
 					chip->pagebuf = realpage;
-				else
+					chip->pagebuf_bitflips = ret;
+				} else {
 					/* Invalidate page cache */
 					chip->pagebuf = -1;
+				}
 				memcpy(buf, chip->buffers->databuf + col, bytes);
 			}
 
@@ -1310,6 +1318,8 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 		} else {
 			memcpy(buf, chip->buffers->databuf + col, bytes);
 			buf += bytes;
+			max_bitflips = max_t(unsigned int, max_bitflips,
+					     chip->pagebuf_bitflips);
 		}
 
 		readlen -= bytes;
@@ -1341,7 +1351,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 	if (mtd->ecc_stats.failed - stats.failed)
 		return -EBADMSG;
 
-	return  mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+	return max_bitflips;
 }
 
 /**
diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index ddfe7e7..067f8ef 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -969,7 +969,8 @@ static int onenand_read_ops_nolock(struct mtd_info *mtd, loff_t from,
 	if (mtd->ecc_stats.failed - stats.failed)
 		return -EBADMSG;
 
-	return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+	/* return max bitflips per ecc step; ONENANDs correct 1 bit only */
+	return mtd->ecc_stats.corrected != stats.corrected ? 1 : 0;
 }
 
 /**