linux-kernel - Re: [PATCH 0/6] platform/x86: lenovo-wmi-{capdata,other}: Add HWMON for fan speed

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Message-ID: <CAFqHKTkBbtSHfu1bXn8tyjvPSmCOMoWdLyNMv=DRQke679SEPA@mail.gmail.com>
Date: Sat, 25 Oct 2025 21:39:20 -0700
From: Derek John Clark <derekjohn.clark@...il.com>
To: Rong Zhang <i@...g.moe>
Cc: Mark Pearson <mpearson-lenovo@...ebb.ca>, Armin Wolf <W_Armin@....de>, 
	Hans de Goede <hansg@...nel.org>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
	Guenter Roeck <linux@...ck-us.net>, platform-driver-x86@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH 0/6] platform/x86: lenovo-wmi-{capdata,other}: Add HWMON
 for fan speed

On Sun, Oct 19, 2025 at 2:05 PM Rong Zhang <i@...g.moe> wrote:
>
> Lenovo WMI Other Mode interface also supports querying or setting fan
> speed RPM. This capability is decribed by LENOVO_CAPABILITY_DATA_00.
> Besides, LENOVO_FAN_TEST_DATA provides reference data for self-test of
> cooling fans, including minimum and maximum fan speed RPM.
>
> This patchset turns lenovo-wmi-capdata01 into a unified driver (now
> named lenovo-wmi-capdata) for LENOVO_CAPABILITY_DATA_{00,01} and
> LENOVO_FAN_TEST_DATA; then adds HWMON support for lenovo-wmi-other:
>
>  - fanX_enable: enable/disable the fan (tunable)
>  - fanX_input: current RPM
>  - fanX_max: maximum RPM
>  - fanX_min: minimum RPM
>  - fanX_target: target RPM (tunable)
>
> This implementation doesn't require all capability data to be available,
> and is capable to expose interfaces accordingly:
>
>  - Having LENOVO_CAPABILITY_DATA_00: exposes fanX_{enable,input,target}
>  - Having LENOVO_CAPABILITY_DATA_01: exposes firmware_attributes
>  - Having LENOVO_FAN_TEST_DATA: exposes fanX_{max,min}
>
> Rong Zhang (6):
>   platform/x86: Rename lenovo-wmi-capdata01 to lenovo-wmi-capdata
>   platform/x86: lenovo-wmi-{capdata,other}: Support multiple Capability
>     Data
>   platform/x86: lenovo-wmi-capdata: Add support for Capability Data 00
>   platform/x86: lenovo-wmi-other: Add HWMON for fan speed RPM
>   platform/x86: lenovo-wmi-capdata: Add support for Fan Test Data
>   platform/x86: lenovo-wmi-other: Report min/max RPM and hide dummy fans
>
>  .../wmi/devices/lenovo-wmi-other.rst          |  32 +
>  drivers/platform/x86/lenovo/Kconfig           |   5 +-
>  drivers/platform/x86/lenovo/Makefile          |   2 +-
>  drivers/platform/x86/lenovo/wmi-capdata.c     | 545 ++++++++++++++++++
>  drivers/platform/x86/lenovo/wmi-capdata.h     |  46 ++
>  drivers/platform/x86/lenovo/wmi-capdata01.c   | 302 ----------
>  drivers/platform/x86/lenovo/wmi-capdata01.h   |  25 -
>  drivers/platform/x86/lenovo/wmi-other.c       | 422 +++++++++++++-
>  8 files changed, 1028 insertions(+), 351 deletions(-)
>  create mode 100644 drivers/platform/x86/lenovo/wmi-capdata.c
>  create mode 100644 drivers/platform/x86/lenovo/wmi-capdata.h
>  delete mode 100644 drivers/platform/x86/lenovo/wmi-capdata01.c
>  delete mode 100644 drivers/platform/x86/lenovo/wmi-capdata01.h
>
>
> base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> --
> 2.51.0
>

The series' intention looks good overall. The composable methods for
additional capdata interfaces is a welcome change. I have a few
comments I'll add for a couple of the patches. My apologies for the
slow review timeline, I've been on travel and wanted to test the
changes before submitting a review.

For testing I'm using my Legion Go 2. It apparently doesn't have the
FAN_TEST_DATA GUID, and the hwmon interface errors on all inputs
despite being visible. I know for the Legion Go series they use a fan
table with 10 auto_set points in the Other Method interface tied to
the platform profile, but the documentation I have says the methods
you're adding here should be available on all models, so that is a bit
strange.

dmesg output:
[    3.995549] lenovo_wmi_cd 362A3AFE-3D96-4665-8530-96DAD5BB300E-13:
registered LENOVO_CAPABILITY_DATA_00 with 33 items
[    4.000266] lenovo_wmi_cd 7A8F5407-CB67-4D6E-B547-39B3BE018154-9:
registered LENOVO_CAPABILITY_DATA_01 with 80 items
[    4.005603] lenovo_wmi_other
DC2A8805-3A8C-41BA-A6F7-092E0089CD3B-3: bound
362A3AFE-3D96-4665-8530-96DAD5BB300E-13 (ops lwmi_cd_component_ops
[lenovo_wmi_capdata])
[    4.005611] lenovo_wmi_other
DC2A8805-3A8C-41BA-A6F7-092E0089CD3B-3: bound
7A8F5407-CB67-4D6E-B547-39B3BE018154-9 (ops lwmi_cd_component_ops
[lenovo_wmi_capdata])
[    4.005614] lenovo_wmi_other
DC2A8805-3A8C-41BA-A6F7-092E0089CD3B-3: fan capdata unavailable

Testing results:
(deck@...o2 hwmon5)$ ls
device  fan1_enable  fan1_input  fan1_target  name  power  subsystem  uevent
(deck@...o2 hwmon5)$ cat fan1_enable
cat: fan1_enable: No data available
(1)(deck@...o2 hwmon5)$ echo 1 | sudo tee fan1_enable
[sudo] password for deck:
1
tee: fan1_enable: Input/output error
(1)(deck@...o2 hwmon5)$ echo 0 | sudo tee fan1_enable
0
tee: fan1_enable: Input/output error
(1)(deck@...o2 hwmon5)$ echo 3000 | sudo tee fan1_target
3000
tee: fan1_target: Input/output error
(1)(deck@...o2 hwmon5)$ cat fan1_input
cat: fan1_input: No such device or address

Thanks,
Derek