Re: [REGRESSION] thermal: per-zone hwmon names break Steam Deck fan control
Armin Wolf <[email protected]>
| Newsgroups | org.kernel.vger.linux-pm,dev.linux.lists.regressions,org.kernel.vger.linux-hwmon,org.kernel.vger.stable |
|---|---|
| Message-ID | <[email protected]> |
Am 30.07.26 um 11:33 schrieb Rafael J. Wysocki (Intel): > Hi, > > On Wed, Jul 29, 2026 at 10:50 PM Matthew Schwartz > <[email protected]> wrote: >> Hello, >> >> After upgrading my Steam Deck OLED to a 7.2-rc kernel, the userspace fan control daemon that I use stopped working. I bisected the regression to d6323469bcfb ("thermal: hwmon: Register a hwmon device for each thermal zone"). >> >> Before this commit, the ACPI thermal-zone hwmon name was acpitz, while after the change it is now acpitz_0. >> >> The device profiles for fan control rely on the exact `acpitz` hwmon naming like the below code snippet: >> >> devices: >> - hwmon_name: acpitz >> nice_name: CPU >> max_temp: 90 >> temp_hysteresis: 0 >> sensor_name: temp1 >> >> So now, the profile fails to load with: >> >> fancontrol.py[40528]: Warning: hwmons not fully loaded, retrying... >> fancontrol.py[40528]: Warning: hwmons not fully loaded, retrying... >> fancontrol.py[40528]: Warning: hwmons not fully loaded, retrying... >> fancontrol.py[40528]: Traceback (most recent call last): >> fancontrol.py[40528]: File "/usr/share/jupiter-fan-control/fancontrol.py", line 606, in <module> >> fancontrol.py[40528]: raise FileNotFoundError("Failed to load hwmons after 10 attempts.") >> fancontrol.py[40528]: FileNotFoundError: Failed to load hwmons after 10 attempts. >> >> Because initialization fails, the daemon never enters its fan-control loop or writes the requested fan target. >> >> This change was also backported to Linux 7.1.5 as commit 996957016bc1, so the regression is present there as well and has led to a userspace ABI regression. I can look at accommodating the change on the userspace side, but it still seemed worth reporting as a kernel regression. >> >> Thanks, >> Matt >> >> #regzbot introduced: d6323469bcfbda91f0aa89b7b39ad45fe822ca5d > Thanks for the report! > > I think that commit d6323469bcfb will need to be reverted. Would it be possible to instead make the new behavior depend on a Kconfig option? This way we would give userspace time to adapt to the new behavior. Removing it completely would mean that userspace will newer adapt. Thanks, Armin Wolf