Re: [PATCH v5 0/7] platform/x86: lenovo-wmi-{capdata,other}: Add HWMON for fan speed

["Derek J. Clark" <derekjohn.clark@gmail.com>]

On November 14, 2025 9:59:12 AM PST, Rong Zhang <i@rong.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)
>
>LENOVO_CAPABILITY_DATA_{00,01} presents on all devices, so
>both binds to lenovo-wmi-other. However, some device does not have
>LENOVO_FAN_TEST_DATA and its presence is described by
>LENOVO_CAPABILITY_DATA_00; hence, the former binds to the latter and a
>callback is used to pass the data to lenovo-wmi-other.
>
>The implementation does not rely on a specific binding sequence. This
>has been fuzz-tested using:
>
>	#!/bin/bash
>
>	DRV_DIR=/sys/bus/wmi/drivers/lenovo_wmi_cd
>	CAPDATA_GUIDS=(
>		$(find "$DRV_DIR"/ -name '*-*-*-*-*-*' -printf "%f ")
>	)
>
>	b() { sudo tee "$DRV_DIR"/bind <<<"$1"; }
>	u() { sudo tee "$DRV_DIR"/unbind <<<"$1"; }
>
>	for guid in "${CAPDATA_GUIDS[@]}"; do
>		u "$guid"
>	done
>
>	while read -rsa perm; do
>		for guid in "${perm[@]}"; do
>			b "$guid"
>		done
>		sensors | grep -A3 lenovo_wmi_other || true
>		for guid in "${perm[@]}"; do
>			u "$guid"
>		done
>	done < <(python3 -c "
>	from itertools import permutations
>	ps = permutations('${CAPDATA_GUIDS[*]}'.split())
>	for p in ps: print(' '.join(p))")
>
>	for guid in "${CAPDATA_GUIDS[@]}"; do
>		b "$guid"
>	done
>
>Tested on ThinkBook 14 G7+ ASP.
>
>Changes in v5:
>- Do not cast pointer to non-pointer or vice versa (thanks kernel test
>  robot)
>- Fix missing include (ditto)
>- Link to v4: https://lore.kernel.org/r/20251113191152.96076-1-i@rong.moe/
>
>Changes in v4:
>- Get rid of wmi_has_guid() (thanks Armin Wolf's inspiration)
>  - Add [PATCH v4 6/7], please review & test
>  - Rework HWMON registration
>    - Collect fan into from capdata00 and capdata_fan separately
>    - Use a callback to collect fan info from capdata_fan
>    - Trigger HWMON registration only if all fan info is collected
>    - Do not check 0x04050000.supported, implied by the presense of
>      capdata_fan
>- Drop Reviewed-by & Tested-by from [PATCH v4 7/7] due to the changes,
>  please review & test
>- Link to v3: https://lore.kernel.org/r/20251031155349.24693-1-i@rong.moe/
>
>Changes in v3:
>- Fix grammar (thanks Derek J. Clark)
>- Link to v2: https://lore.kernel.org/r/20251030193955.107148-1-i@rong.moe/
>
>Changes in v2:
>- Add a workaround for ACPI methods that return a 4B buffer for u32
>  (thanks Armin Wolf)
>- Fix function documentation (thanks kernel test bot)
>- Reword documentation (thanks Derek J. Clark)
>- Squash min/max reporting patch into the initial HWMON one (ditto)
>- Query 0x04050000 for interface availability (ditto)
>  - New parameter "expose_all_fans" to skip this check
>- Enforce min/max RPM constraint on set (ditto)
>  - New parameter "relax_fan_constraint" to disable this behavior
>  - Drop parameter "ignore_fan_cap", superseded by the next one
>  - New parameter "expose_all_fans" to expose fans w/o such data
>- Assume auto mode on probe (ditto)
>- Do not register HWMON device if no fan can be exposed
>- fanX_target: Return -EBUSY instead of raw target value when fan stops
>- Link to v1: https://lore.kernel.org/r/20251019210450.88830-1-i@rong.moe/
>
>Rong Zhang (7):
>  platform/x86: lenovo-wmi-helpers: Convert returned buffer into u32
>  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-capdata: Add support for Fan Test Data
>  platform/x86: lenovo-wmi-capdata: Wire up Fan Test Data
>  platform/x86: lenovo-wmi-other: Add HWMON for fan reporting/tuning
>
> .../wmi/devices/lenovo-wmi-other.rst          |  43 +-
> drivers/platform/x86/lenovo/Kconfig           |   5 +-
> drivers/platform/x86/lenovo/Makefile          |   2 +-
> drivers/platform/x86/lenovo/wmi-capdata.c     | 808 ++++++++++++++++++
> drivers/platform/x86/lenovo/wmi-capdata.h     |  65 ++
> drivers/platform/x86/lenovo/wmi-capdata01.c   | 302 -------
> drivers/platform/x86/lenovo/wmi-capdata01.h   |  25 -
> drivers/platform/x86/lenovo/wmi-helpers.c     |  22 +-
> drivers/platform/x86/lenovo/wmi-other.c       | 511 ++++++++++-
> 9 files changed, 1426 insertions(+), 357 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: 6da43bbeb6918164f7287269881a5f861ae09d7e

Rong,

I'm out of town for the weekend, but I'll bring a Lenovo device with me. If I get some time I'll test the changes while I'm gone, otherwise it will need to wait until Monday.

Thanks,
Derek