From: Mario Limonciello <mario.limoncie...@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
