linux-kernel - [PATCH] mtd: core: handle flashes without OTP gracefully

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Message-Id: <20210702093841.32307-1-michael@walle.cc>
Date:   Fri,  2 Jul 2021 11:38:41 +0200
From:   Michael Walle <michael@...le.cc>
To:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Michael Walle <michael@...le.cc>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] mtd: core: handle flashes without OTP gracefully

There are flash drivers which registers the OTP callbacks although the
flash doesn't support OTP regions and return -ENODATA for these
callbacks if there is no OTP. If this happens, the probe of the whole
flash will fail. Fix it by handling the ENODATA return code and skip
the OTP region nvmem setup.

Fixes: 4b361cfa8624 ("mtd: core: add OTP nvmem provider support")
Reported-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Michael Walle <michael@...le.cc>
---
 drivers/mtd/mtdcore.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index b5ccd3037788..6881d1423dd6 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -880,7 +880,10 @@ static int mtd_otp_nvmem_add(struct mtd_info *mtd)
 
 	if (mtd->_get_user_prot_info && mtd->_read_user_prot_reg) {
 		size = mtd_otp_size(mtd, true);
-		if (size < 0)
+		/* ENODATA means there is no OTP region */
+		if (size == -ENODATA)
+			size = 0;
+		else if (size < 0)
 			return size;
 
 		if (size > 0) {
@@ -896,7 +899,10 @@ static int mtd_otp_nvmem_add(struct mtd_info *mtd)
 
 	if (mtd->_get_fact_prot_info && mtd->_read_fact_prot_reg) {
 		size = mtd_otp_size(mtd, false);
-		if (size < 0) {
+		/* ENODATA means there is no OTP region */
+		if (size == -ENODATA) {
+			size = 0;
+		} else if (size < 0) {
 			err = size;
 			goto err;
 		}
-- 
2.20.1