[PATCH v3] mtd: nand: Fix nand_do_read_oob() return value

[Miquel Raynal]

Starting from commit 041e4575f034 ("mtd: nand: handle ECC errors in
OOB"), nand_do_read_oob() (from the NAND core) did return 0 or a
negative error, and the MTD layer expected it.

However, the trend for the NAND layer is now to return an error or a
positive number of bitflips. Deciding which status to return to the user
belongs to the MTD layer.

Commit e47f68587b82 ("mtd: check for max_bitflips in mtd_read_oob()")
brought this logic to the mtd_read_oob() function while the return value
coming from nand_do_read_oob() (called by the ->_read_oob() hook) was
left unchanged.

Fixes: e47f68587b82 ("mtd: check for max_bitflips in mtd_read_oob()")
Cc: stable at vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal at free-electrons.com>
---


Changes since v2:
  - Correctly return the maximum number of bitflips, not the number of
    bitflips of the last chunk only.

Changes since v1:
  - s/->ecc.read_oob() hook/->_read_oob() hook/ in the commit message
  - Fixed the compilation issue
  

drivers/mtd/nand/nand_base.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 469220065b8b..e4e39890a975 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3794,6 +3794,7 @@ EXPORT_SYMBOL(nand_write_oob_syndrome);
 static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
 			    struct mtd_oob_ops *ops)
 {
+	unsigned int max_bitflips = 0;
 	int page, realpage, chipnr;
 	struct nand_chip *chip = mtd_to_nand(mtd);
 	struct mtd_ecc_stats stats;
@@ -3855,6 +3856,8 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
 		if (!readlen)
 			break;
 
+		max_bitflips = max_t(unsigned int, max_bitflips, ret);
+
 		/* Increment page address */
 		realpage++;
 
@@ -3876,7 +3879,7 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
 	if (mtd->ecc_stats.failed - stats.failed)
 		return -EBADMSG;
 
-	return  mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+	return max_bitflips;
 }
 
 /**
-- 
2.11.0