Arch Linux

agrewal

Member

Registered: 2018-11-23

Posts: 20

[WORKAROUND] Unable to control fan speed in recent kernels

I am unable to control my fan speeds. The device seems to be missing in /sys/devices/platform.

When it worked, ls -l /sys/class/hwmon

total 0
lrwxrwxrwx 1 root root 0 Jan  1 18:52 hwmon0 -> ../../devices/virtual/thermal/thermal_zone0/hwmon0
lrwxrwxrwx 1 root root 0 Jan  1 18:53 hwmon1 -> ../../devices/platform/coretemp.0/hwmon/hwmon1
lrwxrwxrwx 1 root root 0 Jan  1 18:53 hwmon2 -> ../../devices/pci0000:00/0000:00:01.1/0000:02:00.0/hwmon/hwmon2
lrwxrwxrwx 1 root root 0 Jan  1 18:53 hwmon3 -> ../../devices/platform/f71882fg.656/hwmon/hwmon3

Now, ls -l /sys/class/hwmon

total 0
lrwxrwxrwx 1 root root 0 Jan 14 09:59 hwmon0 -> ../../devices/virtual/thermal/thermal_zone0/hwmon0
lrwxrwxrwx 1 root root 0 Jan 14 10:00 hwmon1 -> ../../devices/platform/coretemp.0/hwmon/hwmon1
lrwxrwxrwx 1 root root 0 Jan 14 10:00 hwmon2 -> ../../devices/pci0000:00/0000:00:01.1/0000:02:00.0/hwmon/hwmon2

ls /sys/devices/platform

alarmtimer  microcode  PNP0C0B:00  PNP0C0B:02  PNP0C0B:04  power      regulatory.0  uevent     vesa-framebuffer.0
coretemp.0  pcspkr     PNP0C0B:01  PNP0C0B:03  PNP0C0C:00  reg-dummy  serial8250    vboxdrv.0

sensors-detect is able to find the chip

Driver `f71882fg':
  * ISA bus, address 0x295
    Chip `Fintek F71869A Super IO Sensors' (confidence: 9)

Driver `coretemp':
  * Chip `Intel digital thermal sensor' (confidence: 9)

But pwmconfig can't

Found the following devices:
   hwmon0 is acpitz
   hwmon1 is coretemp
   hwmon2 is nouveau

I'm currently running 4.20.1-arch1-1-ARCH. So far I've just been using 4.19.4-arch1-1-ARCH. My fans work in that kernel, but not in any kernel I've tried since.

Edit: The issue persists in 4.20.2 and 4.20.3. Is there any way to determine the cause short of git bisect?

Edit2: Adding acpi_enforce_resources=lax to the kernel parameters fixes the symptom. I'm still interested in finding out what caused the change and how to actually fix it.

Last edited by agrewal (2019-02-05 21:21:32)