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From: Christian Hemp <c.hemp@phytec.de>
To: barebox@lists.infradead.org
Cc: Stefan Lengfeld <s.lengfeld@phytec.de>
Subject: [PATCH 2/2] mtd: nand: nand_mxs: Fix readtotal calculation
Date: Thu, 20 Oct 2016 15:40:07 +0200	[thread overview]
Message-ID: <1476970807-43811-2-git-send-email-c.hemp@phytec.de> (raw)
In-Reply-To: <1476970807-43811-1-git-send-email-c.hemp@phytec.de>

The calculation of readtotal must be bit alligend. If not the bch core
finds bit flips in every page, because readtotal is too small.
This bug was mostly introduced since commit "51061a9 mtd: nand: nand_mxs:
Add subpage read support".

Tested with:
nand: NAND device: Manufacturer ID: 0x01, Chip ID: 0xd3 (AMD/Spansion
S34ML08G2), 1024MiB, page size: 2048, OOB size: 128

nand: NAND device: Manufacturer ID: 0x2c, Chip ID: 0xdc (Micron
MT29F4G08ABADAWP), 512MiB, page size: 2048, OOB size: 64

nand: NAND device: Manufacturer ID: 0xec, Chip ID: 0xd3 (Samsung NAND
1GiB 3,3V 8-bit), 1024MiB, page size: 2048, OOB size: 64

Signed-off-by: Christian Hemp <c.hemp@phytec.de>
Signed-off-by: Stefan Lengfeld <s.lengfeld@phytec.de>
---
 drivers/mtd/nand/nand_mxs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/nand_mxs.c b/drivers/mtd/nand/nand_mxs.c
index fe955e8..cba0bee 100644
--- a/drivers/mtd/nand/nand_mxs.c
+++ b/drivers/mtd/nand/nand_mxs.c
@@ -728,15 +728,15 @@ static int __mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand
 	uint32_t corrected = 0, failed = 0;
 	uint8_t	*status;
 	unsigned int  max_bitflips = 0;
-	int i, ret, readtotal, nchunks, eccstrength, ecc_parity_size;
+	int i, ret, readtotal, nchunks, eccstrength;
 
 	eccstrength = mxs_nand_get_ecc_strength(mtd->writesize, mtd->oobsize);
 
 	readlen = roundup(readlen, MXS_NAND_CHUNK_DATA_CHUNK_SIZE);
 	nchunks = mxs_nand_ecc_chunk_cnt(readlen);
-	ecc_parity_size = 13 * eccstrength / 8;
-	readtotal = MXS_NAND_METADATA_SIZE +
-		(MXS_NAND_CHUNK_DATA_CHUNK_SIZE + ecc_parity_size) * nchunks;
+	readtotal =  MXS_NAND_METADATA_SIZE;
+	readtotal += MXS_NAND_CHUNK_DATA_CHUNK_SIZE * nchunks;
+	readtotal += DIV_ROUND_UP(13 * eccstrength * nchunks, 8);
 
 	mxs_nand_config_bch(mtd, readtotal);
 
-- 
1.9.1


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  reply	other threads:[~2016-10-20 13:40 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-20 13:40 [PATCH 1/2] nand: imx6: Changed default NAND clock Christian Hemp
2016-10-20 13:40 ` Christian Hemp [this message]
2016-10-21  7:18   ` [PATCH 2/2] mtd: nand: nand_mxs: Fix readtotal calculation Sascha Hauer
2016-10-24  8:51     ` Stefan Lengfeld
2016-10-21  7:11 ` [PATCH 1/2] nand: imx6: Changed default NAND clock Sascha Hauer
2016-10-24  9:20   ` Stefan Lengfeld
2016-10-25  6:21 ` Sascha Hauer

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