mtd: rawnand: brcmnand: Fixed incorrect sub-page ECC status

stable inclusion
from stable-v4.19.231
commit c48771b7f7b086bca5a1094191b33c3c4324bf0b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5646A
CVE: N/A

------------------------------------------------

[ Upstream commit 36415a79 ]

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: 27c5b17c ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
Signed-off-by: Ndavid regan <dregan@mail.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/trinity-478e0c09-9134-40e8-8f8c-31c371225eda-1643237024774@3c-app-mailcom-lxa02Signed-off-by: NSasha Levin <sashal@kernel.org>

Conflicts:
	drivers/mtd/nand/raw/brcmnand/brcmnand.c
Signed-off-by: NCui GaoSheng <cuigaosheng1@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

drivers/mtd/nand/raw/brcmnand/brcmnand.c

@@ -1633,7 +1633,7 @@ 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,