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Bug#1043327: bugs.debian.org: cpufreq stuck at 400MHz under battery power after disabling secure boot

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nbpf

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Aug 9, 2023, 3:50:06 AM8/9/23
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Package: bugs.debian.org
Severity: important
X-Debbugs-Cc: alocin...@gmail.com

Dear Maintainer,

* I have installed Debian bookworm (Linux loki 6.1.0-10-amd64 #1 SMP
PREEMPT_DYNAMIC Debian 6.1.38-2 (2023-07-27) x86_64 GNU/Linux) on a
Thinkpad X270 (Intel(R) Core(TM) i5-7300U).

* I have disabled secure boot to be able to hibernate the system.

* After booting with secure boot *disabled* and *while on battery
power* the CPU freq gets stuck at 400MHz (the lower hardware limit
as reported by cpupower) and the system becomes very slow.

* After booting with secure boot *disabled* and *while on AC power*
the CPU freq is regulated by the governor (powersave or
performance) as expected and the system works fine.

* Rebooting with secure boot *enabled* completely fixes the problem
but then hibernate is not any longer available.

Thanks for looking into this issue,
Nicola

bo...@pik-potsdam.de

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Aug 10, 2023, 5:20:04 AM8/10/23
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Dear all,

as it turns out, the issue has nothing to do with secure boot:

no matter whether secure boot is enabled or disabled, if the CPU
frequency hits the 400MHz min. threshold it gets stuck at that value.

When the CPU frequency hits the 400MHz min. threshold is hard to say,
but it seems to only happen when the laptop is on battery power.

The only reliable way to recover from a situation in which the CPU
frequency is stuck at 400MHz seems to be to connect the computer to the
AC power.

It is perhaps useful to add that setting the min. CPU frequency to
900MHz

> /usr/bin/cpupower -c all frequency-set -g powersave
> /usr/bin/cpupower -c all frequency-set -d 900MHz

is effective

> nicola@loki:~$ sudo cpupower frequency-info
> analyzing CPU 0:
> driver: intel_pstate
> CPUs which run at the same hardware frequency: 0
> CPUs which need to have their frequency coordinated by software: 0
> maximum transition latency: Cannot determine or is not supported.
> hardware limits: 400 MHz - 3.50 GHz
> available cpufreq governors: performance powersave
> current policy: frequency should be within 800 MHz and 3.50 GHz.
> The governor "powersave" may decide which speed to use
> within this range.
> current CPU frequency: Unable to call hardware
> current CPU frequency: 900 MHz (asserted by call to kernel)
> boost state support:
> Supported: yes
> Active: yes

but does not prevent the CPU frequency to occasionally get stuck to
400MHz on battery power.

Best,
Nicola

Ege

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Nov 30, 2023, 7:50:06 AM11/30/23
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Hello,

It's the complete same story at my laptop after I've upgraded my Debian
to Bookworm. Before, there was no issue like this and I was using my
computer for 7 years without any issue like that.

Recently I bought a new laptop and installed Debian Bookworm right away,
and it has the exact same issue. All CPUs are throttled to 400mhz only
while on battery power (I think around 15% battery left) and does not
get back to normal until I plug it to power supply.

I've seen many issues about this "400mhz" issue on web but people were
talking about thermald (which was not installed when I first had this
issue in my new laptop) or Lenovo's only.

My old computer has i5-6200u and the new one has i7-1360P if this is
relevant.
--
Ege
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