The value of "min_input_signal" returned from ATIF on a Framework AMD 13 is "12". This leads to a fairly bright minimum display backlight. Introduce a quirk to override "min_input_signal" to "0" which leads to a much lower minimum brightness, which is still readable even in daylight. Tested on a Framework AMD 13 BIOS 3.05 and Framework AMD 16. One solution would be a fixed firmware version, which was announced but has no timeline. --- Changes in v4: - Switch back to v2 implementation - Add MODULE_DESCRIPTION() - Simplify quirk infrastructure to only handle min backlight quirks. It can be extended if necessary. - Expand documentation. - Link to v3: https://lore.kernel.org/r/20240731-amdgpu-min-backlight-quirk-v3-0-46d40bb21a62@xxxxxxxxxxxxxx Changes in v3: - Switch to cmdline override parameter - Link to v2: https://lore.kernel.org/r/20240623-amdgpu-min-backlight-quirk-v2-0-cecf7f49da9b@xxxxxxxxxxxxxx Changes in v2: - Introduce proper drm backlight quirk infrastructure - Quirk by EDID and DMI instead of only DMI - Limit quirk to only single Framework 13 matte panel - Link to v1: https://lore.kernel.org/r/20240610-amdgpu-min-backlight-quirk-v1-1-8459895a5b2a@xxxxxxxxxxxxxx --- Thomas Weißschuh (3): drm: Add panel backlight quirks drm: panel-backlight-quirks: Add Framework 13 matte panel drm/amd/display: Add support for minimum backlight quirk Documentation/gpu/drm-kms-helpers.rst | 3 + drivers/gpu/drm/Kconfig | 4 ++ drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/amd/amdgpu/Kconfig | 1 + drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++ drivers/gpu/drm/drm_panel_backlight_quirks.c | 77 +++++++++++++++++++++++ include/drm/drm_utils.h | 3 + 7 files changed, 99 insertions(+) --- base-commit: d74da846046aeec9333e802f5918bd3261fb5509 change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a Best regards, -- Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
