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[SOLVED] [ACPI] Cannot scale CPU frequency after updating
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AaylaSecura
Tux's lil' helper
Tux's lil' helper


Joined: 09 Jun 2011
Posts: 122

PostPosted: Thu Jun 22, 2017 12:14 am    Post subject: [SOLVED] [ACPI] Cannot scale CPU frequency after updating Reply with quote

Greetings! I recently updated from 4.8.4 to 4.11.6 and noticed that I can no longer control the CPU frequency scaling. /sys/devices/system/cpu/cpufreq/policy*/scaling_available_frequencies had disappeared and writing to /sys/devices/system/cpu/cpufreq/policy*/scaling_governor returns EINVAL (file is both readable and writable for root and was opened as root with flags O_RDWR). Moreover /sys/devices/system/cpu/cpufreq/policy*/scaling_max_freq went from 2900000 (in 4.8.4) to 3200000, which is too much for my CPU: it's base freq is 2.90 GHz and I don't overclock. I checked dmesg and I saw this
Code:
[    0.209110] ACPI Error: Needed type [Reference], found [Integer] ffff88045cb7ee58 (20170119/exresop-103)
[    0.209123] ACPI Error: Method parse/execution failed [\_PR.CPU0._PDC] (Node ffff88045c8755f0), AE_AML_OPERAND_TYPE (20170119/psparse-543)

which didn't happen in 4.8.4. Sounds like a bug, I saw a few threads here and there reporting this error, but couldn't find any explanation. Here are the kernel config for 4.8.4 and for 4.11.6, the entire CMDLINE is built in, I pass no other options.

P.S. This is a MacBook Pro 2016 with Intel Core i5-5287U.


Last edited by AaylaSecura on Tue Aug 29, 2017 9:58 am; edited 1 time in total
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AaylaSecura
Tux's lil' helper
Tux's lil' helper


Joined: 09 Jun 2011
Posts: 122

PostPosted: Tue Aug 29, 2017 9:57 am    Post subject: Reply with quote

Ok, I finally had time to look into this again and figure out what was causing this. The ACPI error was unrelated. The reason I couldn't write to scaling_governor was because I was attempting to write 'userspace' (which is the governor I've always been using) but this one was not present in scaling_available_governors, even though I had enabled CONFIG_CPU_FREQ_GOV_USERSPACE. Most of the other governors I had included were also unavailable, only powersave and performance were. The reason was that in going from 4.8.4 to 4.11.6 CONFIG_X86_INTEL_PSTATE got enabled and the pstate driver was taking over. Disabling it allows me to use userspace governor.
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