From e3d0810f50add1e63883a993bac9e01603a81b53 Mon Sep 17 00:00:00 2001 From: Mario Limonciello Date: Thu, 4 Jun 2026 09:38:12 -0500 Subject: [PATCH] drm/amd/display: Set default backlight without ACPI support [Why] If BIOS doesn't include ATIF method it will not specify default AC or DC levels. This means that backlight will always start at 0%, which isn't expected behavior. [How] Set default AC and DC level when no valid caps found. Also reduce code duplication for ACPI and non-ACPI cases. Reported-by: Edson Juliano Drosdeck Closes: https://lore.kernel.org/dri-devel/20260526210048.1162477-1-edson.drosdeck@gmail.com/ Reviewed-by: Alex Hung Signed-off-by: Mario Limonciello Signed-off-by: Chenyu Chen Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher --- .../amd/display/amdgpu_dm/amdgpu_dm_backlight.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c index f101aed75bb3..0a861d846677 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c @@ -78,20 +78,16 @@ void amdgpu_dm_update_backlight_caps(struct amdgpu_display_manager *dm, caps->caps_valid = false; } } - - if (!caps->caps_valid) { - caps->min_input_signal = AMDGPU_DM_DEFAULT_MIN_BACKLIGHT; - caps->max_input_signal = AMDGPU_DM_DEFAULT_MAX_BACKLIGHT; - caps->caps_valid = true; - } #else if (caps->aux_support) return; - - caps->min_input_signal = AMDGPU_DM_DEFAULT_MIN_BACKLIGHT; - caps->max_input_signal = AMDGPU_DM_DEFAULT_MAX_BACKLIGHT; - caps->caps_valid = true; #endif + if (!caps->caps_valid) { + caps->min_input_signal = AMDGPU_DM_DEFAULT_MIN_BACKLIGHT; + caps->max_input_signal = AMDGPU_DM_DEFAULT_MAX_BACKLIGHT; + caps->ac_level = caps->dc_level = 50; + caps->caps_valid = true; + } } EXPORT_IF_KUNIT(amdgpu_dm_update_backlight_caps);