From b5a981e1b34e44f94a5967f730fff4166f2101e8 Mon Sep 17 00:00:00 2001
From: Mario Limonciello <mario.limonciello@amd.com>
Date: Sat, 22 Feb 2025 23:37:32 -0600
Subject: [PATCH] drm/amd/display: fix default brightness
[Why]
To avoid flickering during boot default brightness level set by BIOS
should be maintained for as much of the boot as feasible.
commit 2fe87f54abdc ("drm/amd/display: Set default brightness according
to ACPI") attempted to set the right levels for AC vs DC, but brightness
still got reset to maximum level in initialization code for
setup_backlight_device().
[How]
Remove the hardcoded initialization in setup_backlight_device() and
instead program brightness value to match BIOS (AC or DC). This avoids a
brightness flicker from kernel changing the value. Userspace may however
still change it during boot.
Fixes: 2fe87f54abdc ("drm/amd/display: Set default brightness according to ACPI")
Acked-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 0747acf3311229e22009bec4a9e7fc30c879e842)
Cc: stable@vger.kernel.org
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index f4fed93f2915a..4bd7f82c582dc 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4911,6 +4911,7 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
dm->backlight_dev[aconnector->bl_idx] =
backlight_device_register(bl_name, aconnector->base.kdev, dm,
&amdgpu_dm_backlight_ops, &props);
+ dm->brightness[aconnector->bl_idx] = props.brightness;
if (IS_ERR(dm->backlight_dev[aconnector->bl_idx])) {
DRM_ERROR("DM: Backlight registration failed!\n");
@@ -4978,7 +4979,6 @@ static void setup_backlight_device(struct amdgpu_display_manager *dm,
aconnector->bl_idx = bl_idx;
amdgpu_dm_update_backlight_caps(dm, bl_idx);
- dm->brightness[bl_idx] = AMDGPU_MAX_BL_LEVEL;
dm->backlight_link[bl_idx] = link;
dm->num_of_edps++;
--
GitLab