Bug Report: Rock 5b+ Ubuntu FAN is not spining

[tpnthr]

What happened?

So the problem is that fan is not spinning. It is original fan with heat sink from radxa.
SBC is getting pretty hot, but fan is still. When i turn on the device fan moves a bit and is still for entire time.

sudo sh -c 'echo 255 > /sys/class/hwmon/hwmon9/pwm1'; echo $?
shows 0 error and parameter is changed to 255 for a few seconds, but after that parameter is set back to 0. fan do not react to any type of changes.

Maybe someone knows how to make this fan work?

Kernel version

6.1.0-1025-rockchip

SBC model

radxa 5b+

What operating system are you seeing this problem on?

Ubuntu 24.04 LTS (Noble Nombat)

Relevant logs

No response

[lukaszsobala]

To make the manual fan speed be persistent, you need to change the policy to userspace:

echo user_space |sudo tee /sys/class/thermal/thermal_zone0/policy

The fan does not spin because the default profile does not make sense. I recommend this one:
https://forum.radxa.com/t/guide-how-to-make-the-rock-5b-fan-work-properly-joshua-rieks-ubuntu-24-04/20836

If the fan doesn't react, you might want to check if it's plugged in correctly

[tpnthr]

Done everything according to that instructions
Still nothing.
When I plug power to sbc FAN make one rotation and stops - so it should be connected good.

May be there is a way to force fan to certain speed?

[lukaszsobala]

the way to force a certain speed that I know about is echoing some number to pwm1, as you did, with user_space policy. Or you can try powering it with GPIO if you know how to use them.

[cplatt-iso]

If you are actually using the 5B plus and not a 5b, on my stock installation the pwm fan is hwmon10 every boot. You can check the value of /sys/class/hwmon/hwmonX/name where X is some number. One of them will be "pwmfan".

You need to make sure the correct device tree is loaded, see: #1090

You dont need to set user_space policy out of the box, "echo 255 | sudo tee /sys/class/hwmon/hwmon10/pwm1" works for me and set the fan at 100% duty cycle. There is an issue with the device tree and my fan, where it is setting a duty cycle of 64 at the lower end of the temp curve which is not high enough to spin my fan up. I've made a few changes in my file with a higher low-end duty cycle if you want to try it: https://github.com/cplatt-iso/rock5b/blob/master/rk3588-rock-5b-plus.dts