[PATCH v5 0/2] Add support for 'power saving policy' property

[Xaver Hugl]

I have some more concerns / different direction I'd like to go with
this stuff, let's please hold on it for now and talk about it at the
display next hackfest again.

- Xaver

Am Sa., 21. Juni 2025 um 17:27 Uhr schrieb Mario Limonciello
<superm1 at kernel.org>:
>
> From: Mario Limonciello <mario.limonciello at amd.com>
>
> During the Display Next hackfest 2024 one of the topics discussed
> was the need for compositor to be able to relay intention to drivers
> that color fidelity is preferred over power savings.
>
> To accomplish this a new optional DRM property is being introduced called
> "power saving policy".  This property is a bit mask that can be configured
> with requests of "Require color accuracy" or "Require low latency"
> that can be configured by the compositor.
>
> When a driver advertises support for this property and the compositor
> sets it to "Require color accuracy" then the driver will disable any power
> saving features that can compromise color fidelity.
>
> In practice the main feature this currently applies to is the
> "Adaptive Backlight Modulation" feature within AMD DCN on eDP panels.
>
> When the compositor has marked the property  "Require color accuracy" then
> this feature will be disabled and any userspace that tries to turn it on
> will get an -EBUSY return code.
>
> Compositors can also request that low latency is critical which in
> practice should cause PSR and PSR2 to be disabled.
>
> When the compositor has restored the value back to no requirements then
> the previous value that would have been programmed will be restored.
>
> This was previously accepted at version 4 but reverted because userspace
> didn't have a matching implementation.
> One was now created for KDE:
>  * https://invent.kde.org/plasma/kwin/-/merge_requests/6028
>
> There was also a bug reported that Xorg crashed with this change. It's
> fixed by this PR:
>  * https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/-/merge_requests/102
>
> Mario Limonciello (2):
>   drm: Introduce 'power saving policy' drm property
>   drm/amd: Add power_saving_policy drm property to eDP connectors
>
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c   |  4 ++
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 52 +++++++++++++++++--
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  2 +
>  drivers/gpu/drm/drm_connector.c               | 49 +++++++++++++++++
>  include/drm/drm_connector.h                   |  2 +
>  include/drm/drm_mode_config.h                 |  5 ++
>  include/uapi/drm/drm_mode.h                   |  9 ++++
>  7 files changed, 118 insertions(+), 5 deletions(-)
>
> --
> 2.43.0
>