pwm fan spinning down even though fancontrol is active (debian)

[mwip]

Recently, I configured the pwm fan on my HC4 using pwmconfig/fancontrol and supplied the fancontrol config as discussed here #408.

It worked fine for a few weeks. Lately, however, I experience the following quirk:
For no apparent reason, the fan changes from the usual continuous spin of about 1200 to 1500 rpm to a stop-and-go pattern. Then, the fan mostly rests at 0 rpm and only spins up shortly (1-2 seconds) to 200 to sometimes 2000 rpm.

I wonder if this might be caused by an update to a kernel(-module) or similar? Unfortunately I do not have any logs, as I am not quite sure which would help. Let me know and I will kindly provide them.

It seems that a restart fixes it sometimes and even then only for a few days.

I am running the latest debian image.

uname -a
Linux hc4 5.11.0-odroid-arm64 #1 SMP PREEMPT Debian 5.11.6-202103181356~buster (2021-03-18) aarch64 GNU/Linux

[tobetter]

If you are running the Linux kernel "5.11.0-odroid-arm64", please report the issue here https://github.com/tobetter/linux/issues.

For you Fan issue, are you able see the fan info if you run 'sensors'?

[mwip]

Sorry, I didn't know about the other repo. Shall I move the issue?

As for sensors: yes, I monitor the fan speed using watch sensors and that reflects the behavior of the physical fan.

[tobetter]

Looks like the fancontrol is regressed while upgrading recently, sorry about that. I have to rework the code and release it sometime soon. Thank you for letting me know the issue.

[mwip]

I am sorry to add even more to the confusion but I restarted yesterday in order to confirm whether a restart would solve this issue. It didn't. The fan was in the above mentioned weird state. However, today I noticed that the fans were working properly for some reason. I tried journalctl | grep fancontrol but got nothing.