drm/amd/display: fix initial backlight brightness calculation
PATCH v2 1/1 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 <[email protected]>
--- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +2 -2
@@ -4941,9 +4941,9 @@ 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,
Signature · 4 lines
2.50.1 -- Lauri Tirkkonen | lotheac @ IRCnet
Quoted 7 lines · Lauri Tirkkonen
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 <[email protected]>
Thanks so much!
Reviewed-by Mario Limonciello <[email protected]>
Quoted 20 lines
--- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +2
-2@@ -4941,9 +4941,9 @@ 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,