linux-kernel - [PATCH v2] mtd: core: handle flashes without OTP gracefully

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Date:   Wed,  7 Jul 2021 15:53:59 +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>,
        Tudor.Ambarus@...rochip.com, Michael Walle <michael@...le.cc>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH v2] 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>
Tested-by: Guenter Roeck <linux@...ck-us.net>
---
changes since v1:
 - move the check into mtd_otp_size()

 drivers/mtd/mtdcore.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index b5ccd3037788..c8fd7f758938 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -806,7 +806,9 @@ static ssize_t mtd_otp_size(struct mtd_info *mtd, bool is_user)
 
 err:
 	kfree(info);
-	return ret;
+
+	/* ENODATA means there is no OTP region. */
+	return ret == -ENODATA ? 0 : ret;
 }
 
 static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
-- 
2.20.1