mtd: ecc_strength is at ecc step granularity

ecc_strength element of mtd_info will be the strength of one ecc step, not of
the entire writesize, as was previously planned.  This is the appropriate way
because, as was pointed out¹, bit errors in excess of the strength of one
step can cause a hard error if they all occur within the same ecc region.

¹ http://lists.infradead.org/pipermail/linux-mtd/2012-March/040313.html

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/nand_base.c

@@ -3487,7 +3487,7 @@ int nand_scan_tail(struct mtd_info *mtd)
 
 	/* propagate ecc info to mtd_info */
 	mtd->ecclayout = chip->ecc.layout;
-	mtd->ecc_strength = chip->ecc.strength * chip->ecc.steps;
+	mtd->ecc_strength = chip->ecc.strength;
 
 	/* Check, if we should skip the bad block table scan */
 	if (chip->options & NAND_SKIP_BBTSCAN)

include/linux/mtd/mtd.h

@@ -164,7 +164,7 @@ struct mtd_info {
 	/* ECC layout structure pointer - read only! */
 	struct nand_ecclayout *ecclayout;
 
-	/* max number of correctible bit errors per writesize */
+	/* max number of correctible bit errors per ecc step */
 	unsigned int ecc_strength;
 
 	/* Data for variable erase regions. If numeraseregions is zero,