drm/amd/display: Restore guard against default backlight value < 1 nit

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Mark reports that brightness is not restored after Xorg dpms screen blank.

This behavior was introduced by commit d9e865826c ("drm/amd/display:
Simplify brightness initialization") which dropped the cached backlight
value in display code, but also removed code for when the default value
read back was less than 1 nit.

Restore this code so that the backlight brightness is restored to the
correct default value in this circumstance.

Reported-by: Mark Herbert <mark.herbert42@gmail.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3031
Cc: stable@vger.kernel.org
Cc: Camille Cho <camille.cho@amd.com>
Cc: Krunoslav Kovac <krunoslav.kovac@amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Fixes: d9e865826c ("drm/amd/display: Simplify brightness initialization")
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

...

This commit is contained in:

Mario Limonciello 2023-12-06 12:08:26 -06:00 • committed by Alex Deucher

parent 0497ae6f88

commit a2020be694

1 changed files with 2 additions and 2 deletions

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4

drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c

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