[PATCH v3] mtd: rawnand: brcmnand: correctly verify erased pages

[Álvaro Fernández Rojas]

The current code checks that the whole OOB area is erased.
This is a problem when JFFS2 cleanmarkers are added to the OOB, since it will
fail due to the usable OOB bytes not being 0xff.
Correct this by only checking that data and ECC bytes aren't 0xff.

Fixes: 02b88eea9f9c ("mtd: brcmnand: Add check for erased page bitflips")
Signed-off-by: Álvaro Fernández Rojas <noltari at gmail.com>
---
 v3: Fix commit log and merge nand_check_erased_ecc_chunk calls.
 v2: Add Fixes tag

 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index e4e3ceeac38f..80fe01f03516 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -2018,8 +2018,9 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip,
 static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd,
 		  struct nand_chip *chip, void *buf, u64 addr)
 {
+	struct mtd_oob_region oobecc;
 	int i, sas;
-	void *oob = chip->oob_poi;
+	void *oob;
 	int bitflips = 0;
 	int page = addr >> chip->page_shift;
 	int ret;
@@ -2035,11 +2036,19 @@ static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd,
 	if (ret)
 		return ret;
 
-	for (i = 0; i < chip->ecc.steps; i++, oob += sas) {
+	for (i = 0; i < chip->ecc.steps; i++) {
 		ecc_chunk = buf + chip->ecc.size * i;
-		ret = nand_check_erased_ecc_chunk(ecc_chunk,
-						  chip->ecc.size,
-						  oob, sas, NULL, 0,
+
+		if (mtd->ooblayout->ecc(mtd, i, &oobecc)) {
+			oob = NULL;
+			oobecc.length = 0;
+		} else {
+			oob = chip->oob_poi + oobecc.offset;
+		}
+
+		ret = nand_check_erased_ecc_chunk(ecc_chunk, chip->ecc.size,
+						  oob, oobecc.length,
+						  NULL, 0,
 						  chip->ecc.strength);
 		if (ret < 0)
 			return ret;
-- 
2.26.2