[PATCH v4 3/8] mtd: rawnand: Ensure the number of bitflips is consistent

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>, <devicetree@vger.kernel.org>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	<linux-mtd@lists.infradead.org>
Cc: Michal Simek <monstr@monstr.eu>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Naga Sureshkumar Relli <nagasure@xilinx.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>
Subject: [PATCH v4 3/8] mtd: rawnand: Ensure the number of bitflips is consistent
Date: Fri,  8 May 2020 19:13:34 +0200	[thread overview]
Message-ID: <20200508171339.8052-4-miquel.raynal@bootlin.com> (raw)
In-Reply-To: <20200508171339.8052-1-miquel.raynal@bootlin.com>

The main NAND read page function can loop over "page reads" many times
in if the reading reports uncorrectable error(s) and if the chip
supports the read_retry feature.

In this case, the number of bitflips is summarized between
attempts. Fix this by re-initializing the entire mtd_ecc_stats object
each time we retry.

Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/nand/raw/nand_base.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index dda82217e12c..25d298938aa9 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -3235,7 +3235,7 @@ static int nand_do_read_ops(struct nand_chip *chip, loff_t from,
 	oob_required = oob ? 1 : 0;
 
 	while (1) {
-		unsigned int ecc_failures = mtd->ecc_stats.failed;
+		struct mtd_ecc_stats ecc_stats = mtd->ecc_stats;
 
 		bytes = min(mtd->writesize - col, readlen);
 		aligned = (bytes == mtd->writesize);
@@ -3286,7 +3286,7 @@ static int nand_do_read_ops(struct nand_chip *chip, loff_t from,
 			 */
 			if (use_bounce_buf) {
 				if (!NAND_HAS_SUBPAGE_READ(chip) && !oob &&
-				    !(mtd->ecc_stats.failed - ecc_failures) &&
+				    !(mtd->ecc_stats.failed - ecc_stats.failed) &&
 				    (ops->mode != MTD_OPS_RAW)) {
 					chip->pagecache.page = realpage;
 					chip->pagecache.bitflips = ret;
@@ -3309,7 +3309,7 @@ static int nand_do_read_ops(struct nand_chip *chip, loff_t from,
 
 			nand_wait_readrdy(chip);
 
-			if (mtd->ecc_stats.failed - ecc_failures) {
+			if (mtd->ecc_stats.failed - ecc_stats.failed) {
 				if (retry_mode + 1 < chip->read_retries) {
 					retry_mode++;
 					ret = nand_setup_read_retry(chip,
@@ -3317,8 +3317,8 @@ static int nand_do_read_ops(struct nand_chip *chip, loff_t from,
 					if (ret < 0)
 						break;
 
-					/* Reset failures; retry */
-					mtd->ecc_stats.failed = ecc_failures;
+					/* Reset ecc_stats; retry */
+					mtd->ecc_stats = ecc_stats;
 					goto read_retry;
 				} else {
 					/* No more retry modes; real failure */
-- 
2.20.1


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