Obviously, it doesn't work due to missing permissions (even with sudo/ root) because it is /sys: $ sudo su Ack! (Yes, I know I can start the service manually after each login, but that’s not the proper way to solve the problem.I'm trying to lock RPM of my AMD Radeon videocard fans at the full speed: echo 1 > /sys/class/hwmon/hwmon1/pwm1_enable The whole point of Linux is to give us back control of our computers, and then someone makes this decision for us. But I’m running a Ryzen 9 5950X so I’d like to be on the latest stable kernel. This is so annoying I just reverted to 5.10 just to have my fan control back. I can’t find where in the boot sequence to invoke the service to get it to start successfully. (I think I updated the kernel, but I don’t remember.) I made sure the service was enabled, and it was, but it keeps failing at boot. Under, and this worked for a while, then stopped. (I don’t recall which command I used to determine this.) I added: I have tried to find the service that creates hwmon, and it looked to be “rvice”. The last digit of the hwmon device can change between boots or with kernel changes. So the service is being called at a time before the hwmon device is created.

If I start the service manually after I login, it works fine. The problem is that the service keeps failing at boot with the message “invalid hwmon”. Here’s a relevant section of code: hwmon paths, hardcoded for one amdgpu card, adjust as neededįILE_PWM=$(echo /sys/class/drm/card0/device/hwmon/hwmon?/pwm1)įILE_FANMODE=$(echo /sys/class/drm/card0/device/hwmon/hwmon?/pwm1_enable)įILE_TEMP=$(echo /sys/class/drm/card0/device/hwmon/hwmon?/temp1_input)

So, I found the service “amdgpu-fancontrol”, which lets me set a comfortable fan curve. I saw some discussion about this problem existing in 5.10, but apparently it was fixed. The fan doesn’t spin until GPU temperatures reach about 65C. In 5.11 the kernel developers broke something. Up through kernel 5.10, my AMD RX550 GPU fan was happily spinning at low speed keeping my GPU cool under idle - around 35-39C.

Amdgpu fan control