Patchwork mtd: atmel_nand: pmecc: fix bug fail to correct bit error in 1024-bytes sector

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Submitter Wu, Josh
Date Aug. 19, 2013, 10:05 a.m.
Message ID <1376906744-4711-1-git-send-email-josh.wu@atmel.com>
Download mbox | patch
Permalink /patch/268143/
State New
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Comments

Wu, Josh - Aug. 19, 2013, 10:05 a.m.
The PMECC use BCH algorithm to correct error. In BCH algorithm, the primitive
polynomial value is GF(2^13) for 512-bytes sector size. And it is GF(2^14) for
1024-bytes sector size.

This patch will choose correct degree of the remainders(13 or 14) for
different sector size.
Tested in AT91SAM9X5-EK with MLC nand flash.

More detail can be refered to section 5.4.1 of:
  AT91SAM ARM-based Embedded MPU Application Note
  <http://www.atmel.com/Images/doc11127.pdf>

Signed-off-by: Josh Wu <josh.wu@atmel.com>
---
 drivers/mtd/nand/atmel_nand.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
Artem Bityutskiy - Aug. 19, 2013, 1:38 p.m.
On Mon, 2013-08-19 at 18:05 +0800, Josh Wu wrote:
> The PMECC use BCH algorithm to correct error. In BCH algorithm, the primitive
> polynomial value is GF(2^13) for 512-bytes sector size. And it is GF(2^14) for
> 1024-bytes sector size.
> 
> This patch will choose correct degree of the remainders(13 or 14) for
> different sector size.
> Tested in AT91SAM9X5-EK with MLC nand flash.
> 
> More detail can be refered to section 5.4.1 of:
>   AT91SAM ARM-based Embedded MPU Application Note
>   <http://www.atmel.com/Images/doc11127.pdf>
> 
> Signed-off-by: Josh Wu <josh.wu@atmel.com>

Pushed to l2-mtd.git, thanks!

Patch

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 0e365da..8b2eb3e 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -1204,7 +1204,8 @@  static int __init atmel_pmecc_nand_init_params(struct platform_device *pdev,
 	/* set ECC page size and oob layout */
 	switch (mtd->writesize) {
 	case 2048:
-		host->pmecc_degree = PMECC_GF_DIMENSION_13;
+		host->pmecc_degree = (sector_size == 512) ?
+			PMECC_GF_DIMENSION_13 : PMECC_GF_DIMENSION_14;
 		host->pmecc_cw_len = (1 << host->pmecc_degree) - 1;
 		host->pmecc_sector_number = mtd->writesize / sector_size;
 		host->pmecc_bytes_per_sector = pmecc_get_ecc_bytes(