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Tomash

No dvfs (no cpufreq information) on Banana Pi M2 Zero

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Armbianmonitor:

Build on new kernel (5.1), Ubuntu 18.04.

No cpufreq information (0 MHz in htop etc.) also means there's no working frequency scaling. Which for Allwinner H2+ (Banana Pi M2 Zero) means quick hard-hang due to overheating whenever I compile anything non trivial, unless I point a USB Fan on the CPU (which already got a heatsink).

 

Is there any chance of getting cpufreq and dvfs to work?

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21 minutes ago, Tomash said:

any chance of getting cpufreq and dvfs to work?


Yes. It will be sorted out once, but this kernel is still in development which means ... do some research why its not working and fix it. Its regression either in kernel config, some patches are mixed up or not compatible ... who knows. If you want to just use the board, stick to NEXT kernel (4.19.y)

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It's the same in 4.19.

 

/sys/devices/system/cpu/cpufreq/ is an empty directory.

 

How can I help in debugging and fixing it?

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Try build kernel without this patch. (remove patch/kernel/sunxi-next/board-bpi-m2-zero-enable-dvfs.patch and recompile)

 

If this helps, send a PR for both, NEXT and DEV. The problem is probably the same.

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Spot on, disabling this patch (by touch-ing an empty file in userpatches) fixed the issue, I've got cpufreq information and the frequency does change. stress results in dropping the frequency to 800Mhz when the temperature reaches 80 C, perfect.

At least with NEXT, I'll build and test with DEV kernel soon.

 

Should my entire PR be just a removal of this patch file altogether?

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8 hours ago, Tomash said:

Should my entire PR be just a removal of this patch file altogether?


Yes, please.

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12 minutes ago, Tomash said:

I haven't tested DEV build yet.


It's more recent kernel and almost 100% the same issue. No need. Thanks.

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