Commit 160c365b authored by Miquel Raynal's avatar Miquel Raynal Committed by Greg Kroah-Hartman

nand: fix wrong default oob layout for small pages using soft ecc

commit f7f8c175 upstream.

When using soft ecc, if no ooblayout is given, the core automatically
uses one of the nand_ooblayout_{sp,lp}*() functions to determine the
layout inside the out of band data.

Until kernel version 4.6, struct nand_ecclayout was used for that
purpose. During the migration from 4.6 to 4.7, an error shown up in the
small page layout, in the case oob section is only 8 bytes long.

The layout was using three bytes (0, 1, 2) for ecc, two bytes (3, 4)
as free bytes, one byte (5) for bad block marker and finally
two bytes (6, 7) as free bytes, as shown there:

[linux-4.6] drivers/mtd/nand/nand_base.c:52
static struct nand_ecclayout nand_oob_8 = {
	.eccbytes = 3,
	.eccpos = {0, 1, 2},
	.oobfree = {
		{.offset = 3,
		 .length = 2},
		{.offset = 6,
		 .length = 2} }
};

This fixes the current implementation which is incoherent. It
references bit 3 at the same time as an ecc byte and a free byte.

Furthermore, it is clear with the previous implementation that there
is only one ecc section with 8 bytes oob sections. We shall return
-ERANGE in the nand_ooblayout_ecc_sp() function when asked for the
second section.
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@free-electrons.com>
Fixes: 41b207a7 ("mtd: nand: implement the default mtd_ooblayout_ops")
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 227559e6
......@@ -64,8 +64,14 @@ static int nand_ooblayout_ecc_sp(struct mtd_info *mtd, int section,
if (!section) {
oobregion->offset = 0;
if (mtd->oobsize == 16)
oobregion->length = 4;
else
oobregion->length = 3;
} else {
if (mtd->oobsize == 8)
return -ERANGE;
oobregion->offset = 6;
oobregion->length = ecc->total - 4;
}
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment