3

I have a Lenovo Legion 5 pro (2021), I tried installing ubuntu 20.04.

The problem is that I can't seem to change the brightness at all, it is at max.

Laptop Spec

**Processor** 
    AMD Ryzen™ 7 5800H Processor (8 Cores / 16 Threads, 3.20 GHz, up to 4.40 GHz with Max Boost, 4 MB Cache L2 / 16 MB Cache L3)

**Display Type**
    40.64cms (16.0) WQXGA (2560x1600) IPS 500nits Anti-glare 165Hz 100% sRGB Dolby Vision HDR 400 Free-Sync G-Sync DC Dimmer

***Memory*** 
    16 GB SO-DIMM DDR4 3200MHz

**Graphics** 
    NVIDIA® GeForce RTX™ 3060 6GB GDDR6

**Wireless**
    Wi-Fi 6, 802.11ax 2x2 Wi-Fi + Bluetooth® 5.1, M.2 Card

Just scroll down and you will see the details of the laptop, mine is with RTX 3060.

Any kind of help is appreciated, I have also heard that upgrading to ubuntu 21.04 helps?

Edit There is a hack that works xrandr --output DP-4 --brightness 0.5 but again this is a temporary solution and the controller still does not work.

I also tried to change xorg.conf file, i simply added.

Option "RegistryDwords" "EnableBrightnessControl=1"

It did not work. :,)

Edit More weirdness, now the xrandr hack gets disabled automatically and I have to run it again and again.

On top of the if the session gets suspended, the screen does not come back, like it stays blank and sometimes it comes back but it is very very dim. Not sure what's happening there.

Edit (5/12/21) I have started to use the AMD GPU to save power while using the laptop but the issue is not fixed.

Van Wilder
  • 289

4 Answers4

5
If your BIOS is set to dynamic / hybrid mode

Edit grub’s config:

sudo vim /etc/default/grub

Change the line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

To:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"

Then run:

sudo update-grub

And restart the laptop.
(source: VV0JC13CH)

NB On 22.04 it is not necessary and appears to break night light on wayland.

If your BIOS is set to discrete mode (with nvidia driver)

Edit grub’s config:

sudo vim /etc/default/grub

Change the line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

To:

GRUB_CMDLINE_LINUX="nvidia-drm.modeset=1 acpi_backlight=native nvidia.NVreg_RegistryDwords=EnableBrightnessControl=1"

Then run:

sudo update-grub

And restart the laptop.
(source: BertRAMAerts here)

Pierre
  • 204
1

I had the same issue on my L5P 16ACH6H even after editing both grub and xorg.conf like the other answers here mentioned.

What finally solved it for me was to install an OEM kernel. I believe either 20.04c (5.13) or 20.04d (5.14) is required since the Mediatek wireless card drivers requires at least 5.12 to work. In my case I installed 20.04d using

sudo apt install linux-oem-20.04d

and now brightness control works together with WiFi+BT.

d3cbl
  • 26
0

Sometimes the ACPI is implemented improperly on the motherboard. One solution is to add the parameters acpi_osi=linux and acpi_backlight=video to your kernel command lines in Grub.

Open the file /etc/default/grub using gedit or any other text editor. Look for this line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

and change it to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

This would load device specific drivers before default drivers in Linux.

Save and close text editor.

Now update your grub:

sudo update-grub

And reboot and see what happens.

0

This issue is fully fixed (no config/hacks needed) in Linux kernel 5.16.0 (tested in Ubuntu 21.10 with liquorix kernel).

Details: https://gitlab.freedesktop.org/drm/amd/-/issues/1671

Piotr Henryk Dabrowski
  • 374