From: Mario Limonciello (AMD) <[email protected]> At Display Next Hackfest 2026 we reviewed progress moving brightness control into the DRM connector properties.
There is a range LUMINANCE property that will default to 0->0. Once a driver attaches a backlight it will be updated to 1->max. If the panel supports the minimum backlight turning off the display the range can later be updated to 0->max instead of 1->max. The legacy sysfs interface is synchronized with the DRM connector. When a compositor using this feature is loaded, sysfs writes are disabled to prevent legacy tools from going out of sync with the compositor. This has an implementation initially for amdgpu, i915, and Xe with eDP connectors. It can be extended to other connectors like DP for displays that can be controlled via DDC as well later. The following compositors have implemented matching support: * Kwin: https://invent.kde.org/plasma/kwin/-/merge_requests/9298 * Mutter: https://gitlab.gnome.org/swick/mutter/-/commits/wip/kms-luminance-prop * Wlroots: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/5384 --- v5->v6: * Rebase on drm-next * Drop patch 7/11 (Move backlight tracing out of the dc lock) Mario Limonciello (AMD) (10): Revert "backlight: Remove notifier" backlight: add kernel-internal backlight API drm: link connectors to backlight devices DRM: Add support for client indicating support for luminance drm/amd/display: Pass up errors reading actual brightness drm/amd/display: Allow backlight registration to fail drm/amd/display: use drm backlight drm/amd/display: Drop brightness caching in amdgpu_dm drm/bridge: auto-link panel backlight in bridge connector drm/i915/display: use drm backlight drivers/gpu/drm/Kconfig | 1 + drivers/gpu/drm/Makefile | 1 + .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 111 ++--- .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h | 13 - drivers/gpu/drm/bridge/panel.c | 15 + .../gpu/drm/display/drm_bridge_connector.c | 15 +- drivers/gpu/drm/drm_atomic_helper.c | 7 + drivers/gpu/drm/drm_atomic_uapi.c | 59 ++- drivers/gpu/drm/drm_backlight.c | 445 ++++++++++++++++++ drivers/gpu/drm/drm_connector.c | 63 +++ drivers/gpu/drm/drm_drv.c | 8 + drivers/gpu/drm/drm_file.c | 5 + drivers/gpu/drm/drm_ioctl.c | 15 + drivers/gpu/drm/drm_mode_config.c | 7 + drivers/gpu/drm/drm_mode_object.c | 66 ++- drivers/gpu/drm/drm_property.c | 6 + drivers/gpu/drm/drm_sysfs.c | 28 +- .../gpu/drm/i915/display/intel_backlight.c | 4 + drivers/gpu/drm/i915/display/intel_dp.c | 8 + drivers/video/backlight/backlight.c | 97 ++++ include/drm/drm_backlight.h | 51 ++ include/drm/drm_bridge.h | 1 + include/drm/drm_connector.h | 8 + include/drm/drm_file.h | 8 + include/drm/drm_mode_config.h | 5 + include/linux/backlight.h | 63 +++ include/uapi/drm/drm.h | 22 + 27 files changed, 1046 insertions(+), 86 deletions(-) create mode 100644 drivers/gpu/drm/drm_backlight.c create mode 100644 include/drm/drm_backlight.h base-commit: 0e8233409d4f6def051dd42a432c6815bb780d78 -- 2.43.0
