CPU frequency locked at min. after unsuspening on battery

[unfa]

If I restore my system from being suspended to RAM while I don't have an AC adapter plugged-in, the CPU scaling is locked at the lowest value, and I'm unable to change it. It's unlocked as soon as I plug in an AC-adapter.
I wonder if this is a feature of my machine (Dell Latitude 3550) or is it an OS thing.

This frequently makes my system useless when working mobile, as my work requires high CPU speed. This didn't seem to be an issue until recently.

Sorry if I should post this somewhere else, please direct me if you can.

[artek]

What cpu governor is working in your system?
Can you post output of this command:

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cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

I have used this command to change cpu governor to performance:

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echo performance | tee  /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

The best forum to address this issue is your linux distro forum .
I think it's a broken acpi in dell....

[unfa]

Now I tried, and the phenomenon happens every time I disconnect the AC adapter.

When I plug it back in the CPU gets performance back.

However the CPU governor is reported to be ondemand all the time.

[artek]

Try to change to performace governor with this command:

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echo performance | tee  /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

Is it working?
Is this command showing errors?

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dmesg

[unfa]

The governer is being changed fine, but he CPU frequency is unaffected.

dmesg doesn't report any errors. I found something, but it doesn't show up when I plug/unplug the AC adapter, so I think it's not related:

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[36395.298210] NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.

[artek]

The governer is being changed fine, but he CPU frequency is unaffected.

one more idea:
try this to see what is cpu max freq on your system:

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cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

and this to see what cpu frequencies are availble on your system -

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cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

and with it you can set it to max:

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echo MAXFREQNUMBER | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq