[PATCH v2 2/2] mtd: rawnand: omap: Use ECC information from the generic structures

[Miquel Raynal]

The OMAP driver may leverage software BCH logic to locate errors while
using its own hardware to detect the presence of errors. This is
achieved with a "mixed" mode which initializes manually the software
BCH internal logic while providing its own OOB layout.

The issue here comes from the fact that the BCH driver has been
updated to only use generic NAND objects, and no longer depend on raw
NAND structures as it is usable from SPI-NAND as well. However, at the
end of the BCH context initialization, the driver checks the validity
of the OOB layout. At this stage, the raw NAND fields have not been
populated yet while being used by the layout helpers, leading to an
invalid layout.

The solution here is to use the fields from the generic ECC structures
which have already been updated and will always be valid instead of
the raw NAND ones.

Note: I don't know which commit exactly triggered the error, but the
entire migration to a generic BCH driver got merged in one go, so this
should not be a problem for stable backports.

Reported-by: Adam Ford <aford173 at gmail.com>
Fixes: 80fe603160a4 ("mtd: nand: ecc-bch: Stop using raw NAND structures")
Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/nand/raw/omap2.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/omap2.c b/drivers/mtd/nand/raw/omap2.c
index fbb9955f2467..fd09b2a30abb 100644
--- a/drivers/mtd/nand/raw/omap2.c
+++ b/drivers/mtd/nand/raw/omap2.c
@@ -1866,18 +1866,20 @@ static const struct mtd_ooblayout_ops omap_ooblayout_ops = {
 static int omap_sw_ooblayout_ecc(struct mtd_info *mtd, int section,
 				 struct mtd_oob_region *oobregion)
 {
-	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int nsteps = nanddev_get_ecc_nsteps(nand);
+	unsigned int ecc_bytes = nand->ecc.ctx.total / nsteps;
 	int off = BADBLOCK_MARKER_LENGTH;
 
-	if (section >= chip->ecc.steps)
+	if (section >= nsteps)
 		return -ERANGE;
 
 	/*
 	 * When SW correction is employed, one OMAP specific marker byte is
 	 * reserved after each ECC step.
 	 */
-	oobregion->offset = off + (section * (chip->ecc.bytes + 1));
-	oobregion->length = chip->ecc.bytes;
+	oobregion->offset = off + (section * (ecc_bytes + 1));
+	oobregion->length = ecc_bytes;
 
 	return 0;
 }
@@ -1885,7 +1887,9 @@ static int omap_sw_ooblayout_ecc(struct mtd_info *mtd, int section,
 static int omap_sw_ooblayout_free(struct mtd_info *mtd, int section,
 				  struct mtd_oob_region *oobregion)
 {
-	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	unsigned int nsteps = nanddev_get_ecc_nsteps(nand);
+	unsigned int ecc_bytes = nand->ecc.ctx.total / nsteps;
 	int off = BADBLOCK_MARKER_LENGTH;
 
 	if (section)
@@ -1895,7 +1899,7 @@ static int omap_sw_ooblayout_free(struct mtd_info *mtd, int section,
 	 * When SW correction is employed, one OMAP specific marker byte is
 	 * reserved after each ECC step.
 	 */
-	off += ((chip->ecc.bytes + 1) * chip->ecc.steps);
+	off += ((ecc_bytes + 1) * nsteps);
 	if (off >= mtd->oobsize)
 		return -ERANGE;
 
-- 
2.20.1