[Bug 215801] New: Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[Bug 215801] New: Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

            Bug ID: 215801
           Summary: Rmmod'ing amd-pstate doesn't restore acpi-cpufreq
           Product: Power Management
           Version: 2.5
    Kernel Version: 5.17.1
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
          Assignee: linux-pm@vger.kernel.org
          Reporter: aros@gmx.com
        Regression: No

It's nice that you can now replace acpi-cpufreq with amd-pstate using replace=1
but what about the opposite?

Can it be done without rebooting if acpi-cpufreq is built-in?

Would be really nice to have.

Meanwhile some sort of power managerment still works after `rmmod amd-pstate`
because I see that reported frequencies in /proc/cpuinfo change: one or two
random cores are oscillating between 1700 and 2000MHz, all the others are stuck
at 3800MHz.

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[Bug 215801] Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

--- Comment #1 from Artem S. Tashkinov (aros@gmx.com) ---
Huang Rui,

Is this doable or I'm asking too much?

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[Bug 215801] Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

--- Comment #2 from Artem S. Tashkinov (aros@gmx.com) ---
This is still relevant as of Linux 6.6.

Would be great if removing amd-pstate enabled acpi-cpufreq.

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[Bug 215801] Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

Perry Yuan(AMD) (Perry.Yuan@amd.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Perry.Yuan@amd.com

--- Comment #3 from Perry Yuan(AMD) (Perry.Yuan@amd.com) ---
(In reply to Artem S. Tashkinov from comment #2)
> This is still relevant as of Linux 6.6.
> 
> Would be great if removing amd-pstate enabled acpi-cpufreq.

Normally the system hardware needs to reinitialize CPPC and low-level power
management firmware when CPPC driver loading, so it better to change grub
parameters and reboot again.
dynamically removing amd-pstate and load acpi_cpufreq probably cause some
potential issues. 

Perry.

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[Bug 215801] Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

--- Comment #4 from Artem S. Tashkinov (aros@gmx.com) ---
(In reply to Perry Yuan(AMD) from comment #3)
> (In reply to Artem S. Tashkinov from comment #2)
> > This is still relevant as of Linux 6.6.
> > 
> > Would be great if removing amd-pstate enabled acpi-cpufreq.
> 
> Normally the system hardware needs to reinitialize CPPC and low-level power
> management firmware when CPPC driver loading, so it better to change grub
> parameters and reboot again.
> dynamically removing amd-pstate and load acpi_cpufreq probably cause some
> potential issues. 
> 
> Perry.

Could you add this as a note to the amd pstate driver documentation?

Documentation/admin-guide/pm/amd-pstate.rst

Thank you!

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[Bug 215801] Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

Artem S. Tashkinov (aros@gmx.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WILL_NOT_FIX

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[Bug 215801] Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=215801

--- Comment #5 from Perry Yuan(AMD) (Perry.Yuan@amd.com) ---
(In reply to Artem S. Tashkinov from comment #4)
> (In reply to Perry Yuan(AMD) from comment #3)
> > (In reply to Artem S. Tashkinov from comment #2)
> > > This is still relevant as of Linux 6.6.
> > > 
> > > Would be great if removing amd-pstate enabled acpi-cpufreq.
> > 
> > Normally the system hardware needs to reinitialize CPPC and low-level power
> > management firmware when CPPC driver loading, so it better to change grub
> > parameters and reboot again.
> > dynamically removing amd-pstate and load acpi_cpufreq probably cause some
> > potential issues. 
> > 
> > Perry.
> 
> Could you add this as a note to the amd pstate driver documentation?
> 
> Documentation/admin-guide/pm/amd-pstate.rst
> 
> Thank you!


Sure, we can add this to amd-pstate.rst with a new update. 

Perry.

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