[U-Boot] [PATCH] mtd: atmel_nand: pmecc: fix bug fail to correct bit error in 1024-bytes sector

[Josh Wu <josh.wu@atmel.com>]

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(-)

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 96aca00..da83f06 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -827,7 +827,8 @@ static int atmel_pmecc_nand_init_params(struct nand_chip *nand,
 	switch (mtd->writesize) {
 	case 2048:
 	case 4096:
-		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(
-- 
1.7.9.5