diff options
| author | Lauri Tirkkonen <lauri@hacktheplanet.fi> | 2025-07-21 09:59:40 +0900 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2025-07-28 16:25:34 -0400 |
| commit | 9c2883057b3c861879b647f34e8bc448954e8729 (patch) | |
| tree | 27136a777ebd3ee6566aa7ca8cdfc4e9fe380d28 | |
| parent | 1f02f2044bda1db1fd995bc35961ab075fa7b5a2 (diff) | |
drm/amd/display: fix initial backlight brightness calculation
DIV_ROUND_CLOSEST(x, 100) returns either 0 or 1 if 0<x<=100, so the
division needs to be performed after the multiplication and not the
other way around, to properly scale the value.
Fixes: 8b5f3a229a70 ("drm/amd/display: Fix default DC and AC levels")
Signed-off-by: Lauri Tirkkonen <lauri@hacktheplanet.fi>
Cc: stable@vger.kernel.org
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/aH2Q_HJvxKbW74vU@hacktheplanet.fi
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
| -rw-r--r-- | drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 |
1 files changed, 2 insertions, 2 deletions
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 096b23ad4845d..468c9c5a6773e 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -4983,9 +4983,9 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector) caps = &dm->backlight_caps[aconnector->bl_idx]; if (get_brightness_range(caps, &min, &max)) { if (power_supply_is_system_supplied() > 0) - props.brightness = (max - min) * DIV_ROUND_CLOSEST(caps->ac_level, 100); + props.brightness = DIV_ROUND_CLOSEST((max - min) * caps->ac_level, 100); else - props.brightness = (max - min) * DIV_ROUND_CLOSEST(caps->dc_level, 100); + props.brightness = DIV_ROUND_CLOSEST((max - min) * caps->dc_level, 100); /* min is zero, so max needs to be adjusted */ props.max_brightness = max - min; drm_dbg(drm, "Backlight caps: min: %d, max: %d, ac %d, dc %d\n", min, max, |