From: Jordan Friendshuh <jfriendshuh@xes-inc.com>
Date: Wed, 27 Aug 2014 17:45:36 +0000 (-0500)
Subject: mtd: nand: Base BCH ECC bytes on required strength
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=438320dd34a4d0b2b177fbae749c3b9d00532faf;p=openwrt%2Fstaging%2Fblogic.git

mtd: nand: Base BCH ECC bytes on required strength

NAND devices with page sizes over 4 KiB require more than 4-bits of ECC
coverage. This patch calculates the value of ecc_bytes based on a still
assumed 512-byte step size (13-bits) and the ecc_strength.

Example:
Micron M73A devices (8 KiB page) require 8-bit ECC per 512-byte

Signed-off-by: Jordan Friendshuh <jfriendshuh@xes-inc.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 5b5c62712814..4b7e0287b48f 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4035,7 +4035,7 @@ int nand_scan_tail(struct mtd_info *mtd)
 		 */
 		if (!ecc->size && (mtd->oobsize >= 64)) {
 			ecc->size = 512;
-			ecc->bytes = 7;
+			ecc->bytes = DIV_ROUND_UP(13 * ecc->strength, 8);
 		}
 		ecc->priv = nand_bch_init(mtd, ecc->size, ecc->bytes,
 					       &ecc->layout);