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New: Rmmod'ing amd-pstate doesn't restore acpi-cpufreq

Bug 215801 [email protected] 1 participant 7 messages Apr 5, 2022 – Sep 28, 2023

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#0 lore raw

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: [email protected]
          Reporter: [email protected]
        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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#2 lore raw

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

In reply to [email protected]

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

--- Comment #2 from Artem S. Tashkinov ([email protected]) --- This is still relevant as of Linux 6.6.

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

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#3 lore raw

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

In reply to [email protected]

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

--- Comment #4 from Artem S. Tashkinov ([email protected]) --- (In reply to Perry Yuan(AMD) from comment #3)

Quoted 5 lines

(In reply to Artem S. Tashkinov from comment #2)

Quoted 3 lines

This is still relevant as of Linux 6.6.

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

Quoted 7 lines

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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#4 lore raw

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

In reply to [email protected]

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

Perry Yuan(AMD) ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |[email protected]

--- Comment #3 from Perry Yuan(AMD) ([email protected]) --- (In reply to Artem S. Tashkinov from comment #2)

Quoted 3 lines

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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You are receiving this mail because:
You are the assignee for the bug.
#5 lore raw

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

In reply to [email protected]

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

Artem S. Tashkinov ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |RESOLVED
         Resolution|---                         |WILL_NOT_FIX
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#6 lore raw

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

In reply to [email protected]

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

--- Comment #5 from Perry Yuan(AMD) ([email protected]) --- (In reply to Artem S. Tashkinov from comment #4)

Quoted 12 lines

(In reply to Perry Yuan(AMD) from comment #3)

Quoted 11 lines

(In reply to Artem S. Tashkinov from comment #2)

Quoted 3 lines

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.

Quoted 7 lines
Quoted 1 line

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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