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Date: Wed, 24 Jan 2024 18:22:56 +0100
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>, Arnd Bergmann
 <arnd@arndb.de>, regressions@lists.linux.dev, =?UTF-8?B?UmFmYcWCIE1pxYJl?=
 =?UTF-8?B?Y2tp?= <rafal@milecki.pl>, Chen-Yu Tsai <wenst@chromium.org>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>, asahi@lists.linux.dev,
 Sven Peter <sven@svenpeter.dev>, Michael Walle <michael@walle.cc>,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH] nvmem: include bit index in cell sysfs file name
Message-ID: <20240124182256.776c164b@xps-13>
In-Reply-To: <20240122153442.7250-1-arnd@kernel.org>
References: <20240122153442.7250-1-arnd@kernel.org>
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Hi Arnd,

arnd@kernel.org wrote on Mon, 22 Jan 2024 16:34:10 +0100:

> From: Arnd Bergmann <arnd@arndb.de>
>=20
> Creating sysfs files for all Cells caused a boot failure for linux-6.8-rc=
1 on
> Apple M1, which (in downstream dts files) has multiple nvmem cells that u=
se the
> same byte address. This causes the device probe to fail with

o_O	I didn't even know this was allowed...

> [    0.605336] sysfs: cannot create duplicate filename '/devices/platform=
/soc@200000000/2922bc000.efuse/apple_efuses_nvmem0/cells/efuse@a10'
> [    0.605347] CPU: 7 PID: 1 Comm: swapper/0 Tainted: G S                =
 6.8.0-rc1-arnd-5+ #133
> [    0.605355] Hardware name: Apple Mac Studio (M1 Ultra, 2022) (DT)
> [    0.605362] Call trace:
> [    0.605365]  show_stack+0x18/0x2c
> [    0.605374]  dump_stack_lvl+0x60/0x80
> [    0.605383]  dump_stack+0x18/0x24
> [    0.605388]  sysfs_warn_dup+0x64/0x80
> [    0.605395]  sysfs_add_bin_file_mode_ns+0xb0/0xd4
> [    0.605402]  internal_create_group+0x268/0x404
> [    0.605409]  sysfs_create_groups+0x38/0x94
> [    0.605415]  devm_device_add_groups+0x50/0x94
> [    0.605572]  nvmem_populate_sysfs_cells+0x180/0x1b0
> [    0.605682]  nvmem_register+0x38c/0x470
> [    0.605789]  devm_nvmem_register+0x1c/0x6c
> [    0.605895]  apple_efuses_probe+0xe4/0x120
> [    0.606000]  platform_probe+0xa8/0xd0
>=20
> As far as I can tell, this is a problem for any device with multiple cell=
s on
> different bits of the same address. Avoid the issue by changing the file =
name
> to include the first bit number.

There is only one bit number right? We are talking about byte offsets
so this value can only range from 0 to 7? If we understand each other
correctly then why not, I'm fine with the extra ",0" thing.

> Fixes: 0088cbc19276 ("nvmem: core: Expose cells through sysfs")
> Link: https://github.com/AsahiLinux/linux/blob/bd0a1a7d4/arch/arm64/boot/=
dts/apple/t600x-dieX.dtsi#L156
> Cc: regressions@lists.linux.dev
> Cc: Miquel Raynal <miquel.raynal@bootlin.com>
> Cc: Rafa=C5=82 Mi=C5=82ecki <rafal@milecki.pl>
> Cc: Chen-Yu Tsai <wenst@chromium.org>
> Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: asahi@lists.linux.dev
> Cc: Sven Peter <sven@svenpeter.dev>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---

Thanks,
Miqu=C3=A8l