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From:   Michael Walle <michael@walle.cc>
To:     linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Michael Walle <michael@walle.cc>
Subject: [PATCH] mtd: core: provide unique name for nvmem device
Date:   Thu,  4 Nov 2021 14:48:43 +0100
Message-Id: <20211104134843.2642800-1-michael@walle.cc>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

If there is more than one mtd device which supports OTP, there will
be a kernel warning about duplicated sysfs entries and the probing will
fail. This is because the nvmem device name is not unique. Make it
unique by prepending the name of the mtd. E.g. before the name was
"user-otp", now it will be "mtd0-user-otp".

For reference the kernel splash is:
[    4.665531] sysfs: cannot create duplicate filename '/bus/nvmem/devices/user-otp'
[    4.673056] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-next-20211101+ #1296
[    4.680565] Hardware name: Kontron SMARC-sAL28 (Single PHY) on SMARC Eval 2.0 carrier (DT)
[    4.688856] Call trace:
[    4.691303]  dump_backtrace+0x0/0x1bc
[    4.694984]  show_stack+0x24/0x30
[    4.698306]  dump_stack_lvl+0x68/0x84
[    4.701980]  dump_stack+0x18/0x34
[    4.705302]  sysfs_warn_dup+0x70/0x90
[    4.708973]  sysfs_do_create_link_sd+0x144/0x150
[    4.713603]  sysfs_create_link+0x2c/0x50
[    4.717535]  bus_add_device+0x74/0x120
[    4.721293]  device_add+0x330/0x890
[    4.724791]  device_register+0x2c/0x40
[    4.728550]  nvmem_register+0x240/0x9f0
[    4.732398]  mtd_otp_nvmem_register+0xb0/0x10c
[    4.736854]  mtd_device_parse_register+0x28c/0x2b4
[    4.741659]  spi_nor_probe+0x20c/0x2e0
[    4.745418]  spi_mem_probe+0x78/0xbc
[    4.749001]  spi_probe+0x90/0xf0
[    4.752237]  really_probe.part.0+0xa4/0x320
..
[    4.873936] mtd mtd1: Failed to register OTP NVMEM device
[    4.894468] spi-nor: probe of spi0.0 failed with error -17

Fixes: 4b361cfa8624 ("mtd: core: add OTP nvmem provider support")
Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/mtd/mtdcore.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 9186268d361b..fc0bed14bfb1 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -825,8 +825,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
 
 	/* OTP nvmem will be registered on the physical device */
 	config.dev = mtd->dev.parent;
-	/* just reuse the compatible as name */
-	config.name = compatible;
+	config.name = kasprintf(GFP_KERNEL, "%s-%s", dev_name(&mtd->dev), compatible);
 	config.id = NVMEM_DEVID_NONE;
 	config.owner = THIS_MODULE;
 	config.type = NVMEM_TYPE_OTP;
@@ -842,6 +841,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
 		nvmem = NULL;
 
 	of_node_put(np);
+	kfree(config.name);
 
 	return nvmem;
 }
-- 
2.30.2