linux-kernel - [PATCH 2/2] mtd: core: Fix a conflict between MTD and NVMEM on wp-gpios property

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Date:   Sun, 20 Feb 2022 15:14:32 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org,
        Christophe Kerello <christophe.kerello@...s.st.com>,
        stable@...r.kernel.org, Miquel Raynal <miquel.raynal@...tlin.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 2/2] mtd: core: Fix a conflict between MTD and NVMEM on wp-gpios property

From: Christophe Kerello <christophe.kerello@...s.st.com>

Wp-gpios property can be used on NVMEM nodes and the same property can
be also used on MTD NAND nodes. In case of the wp-gpios property is
defined at NAND level node, the GPIO management is done at NAND driver
level. Write protect is disabled when the driver is probed or resumed
and is enabled when the driver is released or suspended.

When no partitions are defined in the NAND DT node, then the NAND DT node
will be passed to NVMEM framework. If wp-gpios property is defined in
this node, the GPIO resource is taken twice and the NAND controller
driver fails to probe.

A new Boolean flag named ignore_wp has been added in nvmem_config.
In case ignore_wp is set, it means that the GPIO is handled by the
provider. Lets set this flag in MTD layer to avoid the conflict on
wp_gpios property.

Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin")
Signed-off-by: Christophe Kerello <christophe.kerello@...s.st.com>
Cc: stable@...r.kernel.org
Acked-by: Miquel Raynal <miquel.raynal@...tlin.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/mtd/mtdcore.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 70f492dce158..eef87b28d6c8 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -546,6 +546,7 @@ static int mtd_nvmem_add(struct mtd_info *mtd)
 	config.stride = 1;
 	config.read_only = true;
 	config.root_only = true;
+	config.ignore_wp = true;
 	config.no_of_node = !of_device_is_compatible(node, "nvmem-cells");
 	config.priv = mtd;

@@ -833,6 +834,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
 	config.owner = THIS_MODULE;
 	config.type = NVMEM_TYPE_OTP;
 	config.root_only = true;
+	config.ignore_wp = true;
 	config.reg_read = reg_read;
 	config.size = size;
 	config.of_node = np;
-- 
2.21.0