[Bug 221505] REGRESSION][amd_pstate] "EPP cannot be set under performance policy" (EBUSY) when switching to performance profile via PPD on 7.1

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=221505

--- Comment #4 from Sergey (sergeyluashkov@gmail.com) ---
(In reply to Mario Limonciello (AMD) from comment #3)
> Did you set CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP

After enabling CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP=y, power-profiles-daemon (PPD)
loses the ability to switch to the power-saver profile. Attempting to set it
via powerprofilesctl set power-saver results in the system defaulting back to
balanced.

Technical details:

Governor limitation:
cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_governors returns
only [performance, powersave].

PPD Failure:
Since only two governors are visible, PPD fails to map the "power-saver"
profile correctly, even though the underlying hardware supports it.

Manual Override:
I discovered that the only way to successfully force the "power-saver" state is
by writing directly to the platform profile:
echo "quiet" | sudo tee
/sys/devices/platform/asus-nb-wmi/platform-profile/platform-profile-25/profile
(Note: The path may vary, but the "quiet" hint works where PPD fails).

Steps to Reproduce:

Enable CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP=y.

Try to set power-saver: powerprofilesctl set power-saver.

Check status: powerprofilesctl get returns balanced.

Expected Result:
PPD should recognize that in active/dynamic_epp mode, "power-saver" should map
to the powersave governor with an EPP hint of power (or quiet at the platform
level)

Actual Result:
PPD is stuck between two profiles (balanced/performance)

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