mtd: nand: read_page() returns max_bitflips

The ecc.read_page() method for nand drivers is changed to return the maximum
number of bitflips that were corrected on any one region covering an ecc step,
This patch doesn't change what the nand code returns to mtd.

This v2 includes the change to the fsl_ifc_nand driver requested by Scott¹.

¹ http://lists.infradead.org/pipermail/linux-mtd/2012-April/040883.html

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by (freescale changes): Scott Wood <scottwood@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 31 insertions, 16 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 671f228d4c7c..8718eaf8269f 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1138,6 +1138,7 @@ static int nand_read_page_swecc(struct mtd_info *mtd, struct nand_chip *chip,
 	uint8_t *ecc_calc = chip->buffers->ecccalc;
 	uint8_t *ecc_code = chip->buffers->ecccode;
 	uint32_t *eccpos = chip->ecc.layout->eccpos;
+	unsigned int max_bitflips = 0;
 
 	chip->ecc.read_page_raw(mtd, chip, buf, page);
 
@@ -1154,12 +1155,14 @@ static int nand_read_page_swecc(struct mtd_info *mtd, struct nand_chip *chip,
 		int stat;
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
-		if (stat < 0)
+		if (stat < 0) {
 			mtd->ecc_stats.failed++;
-		else
+		} else {
 			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
-	return 0;
+	return max_bitflips;
 }
 
 /**
@@ -1180,6 +1183,7 @@ static int nand_read_subpage(struct mtd_info *mtd, struct nand_chip *chip,
 	int datafrag_len, eccfrag_len, aligned_len, aligned_pos;
 	int busw = (chip->options & NAND_BUSWIDTH_16) ? 2 : 1;
 	int index = 0;
+	unsigned int max_bitflips = 0;
 
 	/* Column address within the page aligned to ECC size (256bytes) */
 	start_step = data_offs / chip->ecc.size;
@@ -1244,12 +1248,14 @@ static int nand_read_subpage(struct mtd_info *mtd, struct nand_chip *chip,
 
 		stat = chip->ecc.correct(mtd, p,
 			&chip->buffers->ecccode[i], &chip->buffers->ecccalc[i]);
-		if (stat < 0)
+		if (stat < 0) {
 			mtd->ecc_stats.failed++;
-		else
+		} else {
 			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
-	return 0;
+	return max_bitflips;
 }
 
 /**
@@ -1271,6 +1277,7 @@ static int nand_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
 	uint8_t *ecc_calc = chip->buffers->ecccalc;
 	uint8_t *ecc_code = chip->buffers->ecccode;
 	uint32_t *eccpos = chip->ecc.layout->eccpos;
+	unsigned int max_bitflips = 0;
 
 	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
 		chip->ecc.hwctl(mtd, NAND_ECC_READ);
@@ -1289,12 +1296,14 @@ static int nand_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
 		int stat;
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
-		if (stat < 0)
+		if (stat < 0) {
 			mtd->ecc_stats.failed++;
-		else
+		} else {
 			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
-	return 0;
+	return max_bitflips;
 }
 
 /**
@@ -1320,6 +1329,7 @@ static int nand_read_page_hwecc_oob_first(struct mtd_info *mtd,
 	uint8_t *ecc_code = chip->buffers->ecccode;
 	uint32_t *eccpos = chip->ecc.layout->eccpos;
 	uint8_t *ecc_calc = chip->buffers->ecccalc;
+	unsigned int max_bitflips = 0;
 
 	/* Read the OOB area first */
 	chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
@@ -1337,12 +1347,14 @@ static int nand_read_page_hwecc_oob_first(struct mtd_info *mtd,
 		chip->ecc.calculate(mtd, p, &ecc_calc[i]);
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], NULL);
-		if (stat < 0)
+		if (stat < 0) {
 			mtd->ecc_stats.failed++;
-		else
+		} else {
 			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
-	return 0;
+	return max_bitflips;
 }
 
 /**
@@ -1363,6 +1375,7 @@ static int nand_read_page_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
 	int eccsteps = chip->ecc.steps;
 	uint8_t *p = buf;
 	uint8_t *oob = chip->oob_poi;
+	unsigned int max_bitflips = 0;
 
 	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
 		int stat;
@@ -1379,10 +1392,12 @@ static int nand_read_page_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
 		chip->read_buf(mtd, oob, eccbytes);
 		stat = chip->ecc.correct(mtd, p, oob, NULL);
 
-		if (stat < 0)
+		if (stat < 0) {
 			mtd->ecc_stats.failed++;
-		else
+		} else {
 			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 
 		oob += eccbytes;
 
@@ -1397,7 +1412,7 @@ static int nand_read_page_syndrome(struct mtd_info *mtd, struct nand_chip *chip,
 	if (i)
 		chip->read_buf(mtd, oob, i);
 
-	return 0;
+	return max_bitflips;
 }
 
 /**
@@ -1588,7 +1603,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 	if (oob)
 		ops->oobretlen = ops->ooblen - oobreadlen;
 
-	if (ret)
+	if (ret < 0)
 		return ret;
 
 	if (mtd->ecc_stats.failed - stats.failed)