[MTD] [NAND] S3C2410 Allow unset ecc to be ignored for ecc correction

If a block's ecc field is all 0xff, then ignore the ECC
correction. This is for systems where some of the blocks,
such as the initial cramfs are written without ECC and
need to be loaded on start.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/nand/s3c2410.c

@@ -357,6 +357,14 @@ static int s3c2410_nand_correct_data(struct mtd_info *mtd, u_char *dat,
 	if (diff0 == 0 && diff1 == 0 && diff2 == 0)
 		return 0;		/* ECC is ok */
 
+	/* sometimes people do not think about using the ECC, so check
+	 * to see if we have an 0xff,0xff,0xff read ECC and then ignore
+	 * the error, on the assumption that this is an un-eccd page.
+	 */
+	if (read_ecc[0] == 0xff && read_ecc[1] == 0xff && read_ecc[2] == 0xff
+	    && info->platform->ignore_unset_ecc)
+		return 0;
+
 	/* Can we correct this ECC (ie, one row and column change).
 	 * Note, this is similar to the 256 error code on smartmedia */
 

include/asm-arm/plat-s3c/nand.h

@@ -36,6 +36,8 @@ struct s3c2410_platform_nand {
 	int	twrph0;	/* active time for nWE/nOE */
 	int	twrph1;	/* time for release CLE/ALE from nWE/nOE inactive */
 
+	unsigned int	ignore_unset_ecc : 1;
+
 	int			nr_sets;
 	struct s3c2410_nand_set *sets;