[Bug 2095291] Re: kernel Patch to Fix Low and Inverted Brightness Value on AMD Devices

drm/amd/display: Allow backlight to go below AMDGPU_DM_DEFAULT_MIN_BACKLIGHT
The issue with panel power savings compatibility below
`AMDGPU_DM_DEFAULT_MIN_BACKLIGHT` happens at
`AMDGPU_DM_DEFAULT_MIN_BACKLIGHT` as well.

That issue will be fixed separately, so don't prevent the backlight
brightness from going that low.

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/amd-gfx/be04226a-a9e3-4a45-a83b-6d263c6557d8@t-8ch.de/T/#m400dee4e2fc61fe9470334d20a7c8c89c9aef44f
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

** Patch added: "drm-amd-display-allow-backlight-to-go-below-amdgpu-dm-default-min-backlight.patch"
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2095291/+attachment/5853038/+files/drm-amd-display-allow-backlight-to-go-below-amdgpu-dm-default-min-backlight.patch

** Bug watch added: gitlab.freedesktop.org/drm/amd/-/issues #3020
https://gitlab.freedesktop.org/drm/amd/-/issues/3020

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https://bugs.launchpad.net/bugs/2095291

Title:
kernel Patch to Fix Low and Inverted Brightness Value on AMD Devices

Status in linux package in Ubuntu:
Confirmed

Bug description:
I have a problem on Linux with my "AMD Ryzen 5 5600H with Radeon Graphics" which is brightness is so low & brightness controls inverted. An important detail is the backlight is at max brightness during the grub screen and halfway into the boot process, just around the time when the systemd backlight service is invoked the screen dims all the way down and stays that way.
In my laptop, the LCD panel is connected to the AMD GPU.

Description: Ubuntu 24.04.1 LTS
Release: 24.04
Kernel: 6.8.0-51-generic

The problem is fixed in this gitlab issue and in mainline kernel 6.11.3
Gitlabs Issues is solved by Mario Limonciello: https://gitlab.freedesktop.org/drm/amd/-/issues/3020#note_2568083

Patch for the fix is given in the attachment file

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