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Mario Limonciello's avatar
Mario Limonciello authored
[Why]
To avoid flickering during boot default brightness level set by BIOS
should be maintained for as much of the boot as feasible.
commit 2fe87f54 ("drm/amd/display: Set default brightness according
to ACPI") attempted to set the right levels for AC vs DC, but brightness
still got reset to maximum level in initialization code for
setup_backlight_device().

[How]
Remove the hardcoded initialization in setup_backlight_device() and
instead program brightness value to match BIOS (AC or DC).  This avoids a
brightness flicker from kernel changing the value.  Userspace may however
still change it during boot.

Fixes: 2fe87f54 ("drm/amd/display: Set default brightness according to ACPI")
Acked-by: default avatarWayne Lin <Wayne.Lin@amd.com>
Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Signed-off-by: default avatarTom Chung <chiahsuan.chung@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 0747acf3)
Cc: stable@vger.kernel.org
b5a981e1
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.