[PATCH stable 4.9] mtd: rawnand: brcmnand: Fixed incorrect sub-page ECC status

[Florian Fainelli]

From: david regan <dregan@xxxxxxxx>

commit 36415a7964711822e63695ea67fede63979054d9 upstream

The brcmnand driver contains a bug in which if a page (example 2k byte)
is read from the parallel/ONFI NAND and within that page a subpage (512
byte) has correctable errors which is followed by a subpage with
uncorrectable errors, the page read will return the wrong status of
correctable (as opposed to the actual status of uncorrectable.)

The bug is in function brcmnand_read_by_pio where there is a check for
uncorrectable bits which will be preempted if a previous status for
correctable bits is detected.

The fix is to stop checking for bad bits only if we already have a bad
bits status.

Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
Signed-off-by: david regan <dregan@xxxxxxxx>
Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/trinity-478e0c09-9134-40e8-8f8c-31c371225eda-1643237024774@3c-app-mailcom-lxa02
[florian: make patch apply to 4.14, file was renamed]
Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
---
 drivers/mtd/nand/brcmnand/brcmnand.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
index 40fdc9d267b9..1c8e95cf29d2 100644
--- a/drivers/mtd/nand/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/brcmnand/brcmnand.c
@@ -1637,7 +1637,7 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip,
 					mtd->oobsize / trans,
 					host->hwcfg.sector_size_1k);
 
-		if (!ret) {
+		if (ret != -EBADMSG) {
 			*err_addr = brcmnand_read_reg(ctrl,
 					BRCMNAND_UNCORR_ADDR) |
 				((u64)(brcmnand_read_reg(ctrl,
-- 
2.25.1