drm/amd/display: Indicate when custom brightness curves are in use

[ Upstream commit 68f3c044f3 ]

[Why]
There is a `scale` sysfs attribute that can be used to indicate when
non-linear brightness scaling is in use.  As Custom brightness curves
work by linear interpolation of points the scale is no longer linear.

[How]
Indicate non-linear scaling when custom brightness curves in use and
linear scaling otherwise.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello <superm1@kernel.org>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Mario Limonciello 2025-08-24 15:20:58 -05:00 • committed by Greg Kroah-Hartman
commit e39af94cbd