RPi3 on aarch64-CPU freq scaling and temp sensors broken

[darksky]

I'm using a RPi3 booted into Arch ARM's armv8/aarch64 kernel, but am unable to query the CPU frequency or adjust it (nor can I read the CPU temp). My RPi2 running the armv7/raspberrypi kernel by contrast contains the following but the RPi3 does not:

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/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

Using cpupower doesn't provide the functionality on the RPi3 either:

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# cpupower frequency-info
analyzing CPU 0:
  no or unknown cpufreq driver is active on this CPU
  CPUs which run at the same hardware frequency: Not Available
  CPUs which need to have their frequency coordinated by software: Not Available
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: Not Available
  available cpufreq governors: Not Available
  Unable to determine current policy
  current CPU frequency: Unable to call hardware
  current CPU frequency:  Unable to call to kernel

I'm guessing it is due to a lack of support in the 4.10.1 kernel but wanted to check. Thanks.

[dukla2000]

I believe this is a kernel issue: oddly enough 4.4 aarch64 kernel in opensuse LEAP 42 has decent support (on demand & performance as well as temp) whereas 4.9 aarch64 kernel in tumbleweed has nothing as per your Arch 4.10 experience. Also (for opensuse aarch64) 4.4 LEAP has WiFi support whereas 4.9 tumbleweed does not (yet).

[darksky]

Thanks for the reply. Glad to hear that it isn't a general problem.

[darksky]

...so is this in fact an upstream kernel bug?

[dukla2000]

...so is this in fact an upstream kernel bug?

The subtleties of what is kernel/upstream/downstream etc or Foundation/Raspbian hacked are beyond me. But it does seem odd to me as well that >=4.8 kernels, which are supposed to have better Pi3 CPU support, seem to lack some basics.

[darksky]

The subtleties of what is kernel/upstream/downstream etc or Foundation/Raspbian hacked are beyond me. But it does seem odd to me as well that >=4.8 kernels, which are supposed to have better Pi3 CPU support, seem to lack some basics.

Yes, but it does matter when targeting someone for a bug report...

[darksky]

Using tardis for Arch ARM, I can go back to an older kernel package... which of the 4.8 kernels do you know worked? I see 4.8.0 through 4.8.14 available there for testing on my machine.

[darksky]

Booting into 4.8.14 gives no sensors/scaling governor support. Same is true for 4.8.2... so the original question remains unanswered: how can one get temp and cpu scaling under aarch64?

[dukla2000]

... so the original question remains unanswered: how can one get temp and cpu scaling under aarch64?

The 4.4.49 aarch64 kernel in OpenSUSE LEAP 42.2 does things fine, available here. My top tip if installing as per their instructions here: after the xzcat | dd remove the card from your machine, reinsert and fsck both partitions. Re-burn if you get any errors (apart from dirty bit on p1).

[darksky]

... so the original question remains unanswered: how can one get temp and cpu scaling under aarch64?

The 4.4.49 aarch64 kernel in OpenSUSE LEAP 42.2 does things fine, available here. My top tip if installing as per their instructions here: after the xzcat | dd remove the card from your machine, reinsert and fsck both partitions. Re-burn if you get any errors (apart from dirty bit on p1).

Interesting.... I grabbed openSUSE-Tumbleweed-ARM-JeOS-raspberrypi3.aarch64.raw.xz which ships with 4.9.6-1 and neither the temp sensor nor the governor are available there either:

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#  uname -r
4.9.6-1-default

# lscpu
Architecture:          aarch64

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq: No such file or directory

# cat /sys/devices/virtual/thermal/thermal_zone0/temp
cat: /sys/devices/virtual/thermal/thermal_zone0/temp: No such file or directory

I will try the image you recommended, openSUSE-Leap42.2-ARM-JeOS-raspberrypi3.aarch64.raw.xz and report back shortly.

[darksky]

It worked! So the question now is why doesn't it work with a current kernel?

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# uname -r
4.4.49-16-default

# lscpu
Architecture:          aarch64

# cat /sys/devices/virtual/thermal/thermal_zone0/temp
42932

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
1200000

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
ondemand

[dukla2000]

So the question now is why doesn't it work with a current kernel?

Yup, $1m! I am struggling to find the OpenSuSE bods who know - despite using SuSE on my desktop for 15+ years the Pi3/aarch64 skills are well hidden, probably embedded deep in the SLE offices somewhere. They clearly had the ability to get things working in the 4.4 kernel in LEAP 42.2 (and presumably SLE) and their aarch64/SLE announcement talks about upstream/downstream but for whatever reason their Tumbleweed releases (whether upstream or non-upstream) that I have tried with 4.9 kernel are a giant leap backwards. Not only this (scaling, temp sensors) but also can't (yet) get onboard wifi to work (but it does on LEAP 42.2 aarch64).

[darksky]

https://github.com/raspberrypi/linux/issues/1918