Pi 3B+ CPU governor/frequency readout not working?

Troubleshooting
21

Ah sorry, I accidentally looked at the “armv7l” contained in Joulinar’s .hw_model output, but you found the solution already :slight_smile:.

So then it is an issue with the latest kernel. Can you report this to RPi kernel devs, please: https://github.com/raspberrypi/linux/issues

22

I did some more testing on it and it seems to be fixed on next LTS kernel already

current version 5.10.92

root@DietPi3:~# uname -a
Linux DietPi3 5.10.92-v8+ #1514 SMP PREEMPT Mon Jan 17 17:39:38 GMT 2022 aarch64 GNU/Linux
root@DietPi3:~# journalctl -u dietpi-preboot.service
-- Journal begins at Mon 2022-02-07 09:42:20 CET, ends at Mon 2022-02-07 09:56:59 CET. --
Feb 07 09:42:22 DietPi3 systemd[1]: Starting DietPi-PreBoot...
Feb 07 09:42:22 DietPi3 DietPi-PreBoot[363]: DietPi-CPU_set | CPU governors are not available on this system. This is probably a virtual machine. Aborting...
Feb 07 09:42:22 DietPi3 systemd[1]: Finished DietPi-PreBoot.
root@DietPi3:~#

Next LTS version 5.15.18

root@DietPi3:~# uname -a
Linux DietPi3 5.15.18-v8+ #1520 SMP PREEMPT Fri Feb 4 12:04:45 GMT 2022 aarch64 GNU/Linux
root@DietPi3:~# journalctl -u dietpi-preboot.service
-- Journal begins at Mon 2022-02-07 10:31:17 CET, ends at Mon 2022-02-07 10:32:01 CET. --
Feb 07 10:31:19 DietPi3 systemd[1]: Starting DietPi-PreBoot...
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]:  DietPi-CPU_set
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]: ─────────────────────────────────────────────────────
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]:  Mode: Applying CPU governor settings: ondemand
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]: [ INFO ] DietPi-CPU_set | Setting up_threshold: 50 %
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]: [ INFO ] DietPi-CPU_set | Setting sampling_rate: 25000 microseconds
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]: [ INFO ] DietPi-CPU_set | Setting sampling_down_factor: 40 x
Feb 07 10:31:19 DietPi3 DietPi-PreBoot[366]: [  OK  ] DietPi-CPU_set | Applied CPU governor settings: ondemand
Feb 07 10:31:19 DietPi3 systemd[1]: Finished DietPi-PreBoot.
root@DietPi3:~#
23

That’s good to know!
I filed a bug report but it doesn’t seem to affect everyone with a Pi 3B+ which is odd.

But the bug must have been recognized at some point if it was fixed in the next kernel…

24

I have answered on RPI GitHub. https://github.com/raspberrypi/linux/issues/4875

25

Seems an alternative to downgrading the Kernel is to remove initial_turbo=20 from config.txt, or enter 0 for initial turbo in Dietpi-Config.
Once I did this and rebooted, CPU governor works even with the 5.10.92 Kernel.

26

let’s what RPI devs will find out.

27

Was anyone with an ARMv7 kernel affected btw, or ARMv8/64-bit systems only? I want to ship a live patch, to have commented the initial turbo setting until it a new kernel has been released which is not affected anymore. But makes sense to only apply it where really required.

28

I killed my ARMv6 installation this evening. Need to re-flash. I can do testing tomorrow during day time for ARMv6/7 images on RPi3B+.

29

had a little time to test this some more today… seems to be resolved on current firmware


boot-DAT-ELF_20220115_175984a6dc4c321553e295cf9679a6020231caf4/ GOOD
boot-DAT-ELF_20220117_20c5829b0afe5b99d7e807ce90c382bd6997993f/ NOTGOOD<PROBLEM
boot-DAT-ELF_20220118_3f20b832b27cd730deb6419b570f31a98167eef6/ STILLNOTGOOD
boot-DAT-ELF_20220121_827fdd073638fa7b7292d1148fe0af7465111eae/ STILLNOTGOOD
boot-DAT-ELF_20220125_9c04ed2c1ad06a615d8e6479806ab252dbbeb95a/ GOOD>FIXED
boot-DAT-ELF_20220128_e5013c9d596e1a392e5193bc8cb822966b9c7d7c/ GOOD
boot-DAT-ELF_20220219_a6496ae5cd5e9b4cd5b38f7274fa94dce315fa7a/ GOODCURRENT

linked issue from the commit which fixed it…

https://github.com/raspberrypi/firmware/issues/1688

30

at least it’s not dedicated to a DietPi issue. But good it will/was solved upstream.