Improve performance and idle power consumption

I tried this on a Ryzen 5 2500U but couldn't see any differences. That was the only AMD system I can have physical access at the moment.

Which CPU or platform is supported by this patch?

What test did you use?
It should be pronounced/notable on Ryzen 5000, particularly using speedometer for the test.

Also can you confirm the platform that you're using has ACPI C3 exported? If it doesn't you'll need a platform with C3.

I only measured idle power.

Thanks. I will try to find Ryzen 5000 for testing.

Status updates:

This patch is not in mainline as 5.15rc2.

The maintainer listed his reasons here: https://lore.kernel<email address hidden>/

It was resubmitted here with a guard to only run on Zen+ CPUs.
https://<email address hidden>/

Here it is in linux-next: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=a8fb40966f19ff81520d9ccf8f7e2b95201368b8

https://lists.ubuntu.com/archives/kernel-team/2021-October/124766.html

This bug is awaiting verification that the linux-oem-5.14/5.14.0-1006.6 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal' to 'verification-done-focal'. If the problem still exists, change the tag 'verification-needed-focal' to 'verification-failed-focal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

This bug was fixed in the package linux-oem-5.14 - 5.14.0-1007.7

---------------
linux-oem-5.14 (5.14.0-1007.7) focal; urgency=medium

  * focal/linux-oem-5.14: 5.14.0-1007.7 -proposed tracker (LP: #1949349)

  * Intel I225-IT ethernet controller: igc: probe of 0000:02:00.0 failed with
    error -1 (LP: #1945576)
    - igc: Remove _I_PHY_ID checking
    - igc: Remove phy->type checking

  * Fix Screen freeze after resume from suspend with iGPU [1002:6987]
    (LP: #1949050)
    - drm/amdgpu: reenable BACO support for 699F:C7 polaris12 SKU
    - drm/amdgpu: add missing cleanups for Polaris12 UVD/VCE on suspend
    - drm/amdgpu: Fix crash on device remove/driver unload

  * Fail to detect audio output from external monitor (LP: #1948767)
    - ALSA: hda: intel: Allow repeatedly probing on codec configuration errors

  * Fix System hangs on black screen when reboot (LP: #1949321)
    - SAUCE: drm/i915: Don't request GMBUS to generate irqs when called while irqs
      are off
    - SAUCE: drm/i915/hdmi: Turn DP++ TMDS output buffers back on in
      encoder->shutdown()

 -- Timo Aaltonen <email address hidden> Mon, 01 Nov 2021 12:38:15 +0200