6.16-stable review patch. If anyone has any objections, please let me know.
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From: Lauri Tirkkonen lauri@hacktheplanet.fi
commit 9c2883057b3c861879b647f34e8bc448954e8729 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -4952,9 +4952,9 @@ amdgpu_dm_register_backlight_device(stru 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,