stable inclusion
from stable-5.10.58
commit bb65051dcd1fd380a73ca52c87f89522e15bf62d
bugzilla: 176984 https://gitee.com/openeuler/kernel/issues/I4E2P4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bb65051dcd1fd380a73ca52c87f89522e15bf62d

--------------------------------

[ Upstream commit f2ad3acc ]

We've gotten a number of reports about backlight control not
working on panels which indicate that they use aux backlight
control.  A recent patch:

commit 2d73eabe
Author: Camille Cho <Camille.Cho@amd.com>
Date:   Thu Jul 8 18:28:37 2021 +0800

    drm/amd/display: Only set default brightness for OLED

    [Why]
    We used to unconditionally set backlight path as AUX for panels capable
    of backlight adjustment via DPCD in set default brightness.

    [How]
    This should be limited to OLED panel only since we control backlight via
    PWM path for SDR mode in LCD HDR panel.
Reviewed-by: NKrunoslav Kovac <krunoslav.kovac@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NCamille Cho <Camille.Cho@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Changes some other code to only use aux for backlight control on
OLED panels.  The commit message seems to indicate that PWM should
be used for SDR mode on HDR panels.  Do something similar for
backlight control in general.  This may need to be revisited if and
when HDR started to get used.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1438
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=213715Reviewed-by: NRoman Li <Roman.Li@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>