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6fd83a1c2c
Custom brightness curves use an 8-bit input signal. After exporting the
full PWM range to userspace, the curve normalizer still divides requests
by the physical PWM span. On panels with a nonzero minimum PWM level,
this can produce a curve input greater than 255 and send an invalid
backlight level to DC.
Scale the userspace [0..max] range to the curve's [0..255] range
instead. This retains the full advertised range and keeps the reverse
readback conversion unchanged.
Fixes: 8dbd72cb79 ("drm/amd/display: Export full brightness range to userspace")
Cc: stable@vger.kernel.org
Signed-off-by: Akhmed Zhitaev <zhitaevakh@gmail.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
(Move to amdgpu_dm_backlight.c)
Link: https://patch.msgid.link/20260813170959.22073-1-zhitaevakh@gmail.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>