From: Arnd Bergmann <arnd@kernel.org>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Miquel Raynal <miquel.raynal@bootlin.com>
Cc: "Arnd Bergmann" <arnd@arndb.de>,
regressions@lists.linux.dev, "Rafał Miłecki" <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: [PATCH] nvmem: include bit index in cell sysfs file name
Date: Mon, 22 Jan 2024 16:34:10 +0100 [thread overview]
Message-ID: <20240122153442.7250-1-arnd@kernel.org> (raw)
From: Arnd Bergmann <arnd@arndb.de>
Creating sysfs files for all Cells caused a boot failure for linux-6.8-rc1 on
Apple M1, which (in downstream dts files) has multiple nvmem cells that use the
same byte address. This causes the device probe to fail with
[ 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
As far as I can tell, this is a problem for any device with multiple cells on
different bits of the same address. Avoid the issue by changing the file name
to include the first bit number.
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: Rafał Miłecki <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>
---
This might not be the fix we want upstream, but it illustrates the issue and
I have successfully tested that this lets me boot v6.8-rc1 on my workstation
again.
Feel free to just treat this as a bug report and suggest a different fix.
As the ABI was only introduced in 6.8-rc1, it can still be changed without
causing other regressions for users, but time is running out for that.
---
Documentation/ABI/testing/sysfs-nvmem-cells | 16 ++++++++--------
drivers/nvmem/core.c | 5 +++--
2 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-nvmem-cells b/Documentation/ABI/testing/sysfs-nvmem-cells
index 7af70adf3690..c7c9444f92a8 100644
--- a/Documentation/ABI/testing/sysfs-nvmem-cells
+++ b/Documentation/ABI/testing/sysfs-nvmem-cells
@@ -4,18 +4,18 @@ KernelVersion: 6.5
Contact: Miquel Raynal <miquel.raynal@bootlin.com>
Description:
The "cells" folder contains one file per cell exposed by the
- NVMEM device. The name of the file is: <name>@<where>, with
- <name> being the cell name and <where> its location in the NVMEM
- device, in hexadecimal (without the '0x' prefix, to mimic device
- tree node names). The length of the file is the size of the cell
- (when known). The content of the file is the binary content of
- the cell (may sometimes be ASCII, likely without trailing
- character).
+ NVMEM device. The name of the file is: "<name>@<byte>,<bit>",
+ with <name> being the cell name and <where> its location in
+ the NVMEM device, in hexadecimal bytes and bits (without the
+ '0x' prefix, to mimic device tree node names). The length of
+ the file is the size of the cell (when known). The content of
+ the file is the binary content of the cell (may sometimes be
+ ASCII, likely without trailing character).
Note: This file is only present if CONFIG_NVMEM_SYSFS
is enabled.
Example::
- hexdump -C /sys/bus/nvmem/devices/1-00563/cells/product-name@d
+ hexdump -C /sys/bus/nvmem/devices/1-00563/cells/product-name@d,0
00000000 54 4e 34 38 4d 2d 50 2d 44 4e |TN48M-P-DN|
0000000a
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 1d77724f367d..9616c6001b3c 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -460,8 +460,9 @@ static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
list_for_each_entry(entry, &nvmem->cells, node) {
sysfs_bin_attr_init(&attrs[i]);
attrs[i].attr.name = devm_kasprintf(&nvmem->dev, GFP_KERNEL,
- "%s@%x", entry->name,
- entry->offset);
+ "%s@%x,%x", entry->name,
+ entry->offset,
+ entry->bit_offset);
attrs[i].attr.mode = 0444;
attrs[i].size = entry->bytes;
attrs[i].read = &nvmem_cell_attr_read;
--
2.39.2
next reply other threads:[~2024-01-22 15:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-22 15:34 Arnd Bergmann [this message]
2024-01-22 16:55 ` [PATCH] nvmem: include bit index in cell sysfs file name Srinivas Kandagatla
2024-02-09 9:09 ` Linux regression tracking (Thorsten Leemhuis)
2024-02-09 10:20 ` Arnd Bergmann
2024-01-24 17:22 ` Miquel Raynal
2024-01-24 19:49 ` Arnd Bergmann
2024-01-24 22:11 ` Miquel Raynal
2024-01-25 12:15 ` Arnd Bergmann
2024-01-25 13:06 ` Miquel Raynal
-- strict thread matches above, loose matches on Subject: below --
2024-02-09 16:34 srinivas.kandagatla
2024-02-09 16:49 ` Eric Curtin
2024-02-13 19:20 ` Miquel Raynal
2024-02-14 15:28 ` Greg KH
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