[Bug 221569] Laptop fan too loud (spinning nearly always) hp-wmi 7.1-rc4 kerenel

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=221569

--- Comment #36 from Marco Scardovi (scardracs@disroot.org) ---
Thanks for the details.

Looking at the trip points for acpitz, there are only critical, hot, and
passive thresholds, but no active trip points. This confirms that the OS
thermal subsystem has no direct control over the fan via ACPI tables; the fan
is controlled entirely by the Embedded Controller (EC) firmware.

Even with the CPU idling at 37°C, the MediaTek WiFi 7 card (mt7925) is still
running very hot at 79°C. In many modern designs, the EC will keep the fan
spinning at a minimum speed (2100 RPM in your case) if any monitored component
(like the WiFi module or NVMe) is hot, to prevent localized heat build-up.

To test if the WiFi module is indeed the one triggering the fan, you can try
this quick test:

Block/disable WiFi and Bluetooth completely:

> sudo rfkill block all

Wait a few minutes (with the system idle) to see if the mt7925 temperature
drops.
Check sensors again to see if the WiFi temp drops and if the fan under acpi_fan
slows down or turns off.
If the fan turns off, it confirms the fan is triggered by the WiFi card's idle
temperature. (You can re-enable it later with sudo rfkill unblock all).

Additionally, you can check if you have any exposed ACPI cooling devices in
sysfs:

> tail /sys/class/thermal/cooling_device*/type
> tail /sys/class/thermal/cooling_device*/cur_state

Sometimes you can read the current fan state there, though the EC usually
overrides any manual changes to cur_state.

Another suggestion I can give you, if you feel confident enough, it to open the
chassis and check for dust around the WiFi module.

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