#StackBounty: #nvidia #20.04 #screen #brightness #backlight Cannot adjust screen backlight Ubuntu 20.04 on Lenovo Legion Y7000P2020H

Bounty: 50

I have Ubuntu 20.04 installed on my Lenovo Y7000P2020H laptop alongside Windows 10. I can adjust my screen brightness in Windows but not in Ubuntu 20.04. Neither the fn keys nor the brightness scroll bar works.

More specific system information:

  • Laptop model: Lenovo Y7000P2020H
  • OS: Ubuntu 20.04.1 LTS
  • CPU: Interl Core i7-10750H CPU@1.60GHzx12
  • GPU: Nvidia RTX2060, Graphics Device/PCIe/SSE2
  • GNOME: 3.36.3
  • Windowing System: X11

I’d really like a solution that make the fn keys work. Please don’t suggest brightness-controller and other methods that I have to use command lines. I’ve tried them and they are really inconvenient for me.


I’ve practically tried every solution I can find online, but nothing works:

1. Modifying /etc/default/grub

As suggested in various posts, I’ve tried

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=native"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"

Neither works.

2. xbacklight control, as in the first solution of this answer

Got stuck at step 5 with an error message:

ln: failed to create symbolic link '/sys/class/brightness': Operation not permitted

3 Creating usr/share/X11/xorg.conf.d/20-intel.conf, as in the second solution of this answer

This results in small green and purple blocks to appear on my screen.

4 Change default graphics card using prime-select

I did prime-select intel. After reboot the Nvidia GPU becomes unavailable:

user@pcname:~$ nvidia-smi
NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running.

None of these works. But during the attempts I started to have the suspicion that my screen may be using the Nvidia graphics card for displaying and not the graphics card integrated in my Intel CPU.

One reason is that there are always two Xorg processes running on my Nvidia GPU:

Mon Nov 16 10:52:35 2020       
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 440.33.01    Driver Version: 440.33.01    CUDA Version: 10.2     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  Graphics Device     On   | 00000000:01:00.0 Off |                  N/A |
| N/A   43C    P8     4W /  N/A |    346MiB /  5934MiB |     10%      Default |
+-------------------------------+----------------------+----------------------+
                                                                               
+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID   Type   Process name                             Usage      |
|=============================================================================|
|    0      1188      G   /usr/lib/xorg/Xorg                            45MiB |
|    0      1977      G   /usr/lib/xorg/Xorg                           110MiB |
|    0      2160      G   /usr/bin/gnome-shell                         105MiB |
|    0      2634      G   ...AAAAAAAAAAAACAAAAAAAAAA= --shared-files    67MiB |
|    0      5309      G   gnome-control-center                           3MiB |
+-----------------------------------------------------------------------------+

Moreover, in /usr/share/X11/xorg.conf.d/ there is no config file related to intel, but there are a few with nvidia in their names:

user@pcname:/usr/share/X11/xorg.conf.d$ ls
10-amdgpu.conf  10-quirks.conf  11-nvidia-prime.conf  70-wacom.conf
10-nvidia.conf  10-radeon.conf  40-libinput.conf

In 10-nvidia.conf:

Section "OutputClass"
    Identifier "nvidia"
    MatchDriver "nvidia-drm"
    Driver "nvidia"
    Option "AllowEmptyInitialConfiguration"
    Option "EnableBrightnessControl=1"
    ModulePath "/usr/lib/x86_64-linux-gnu/nvidia-440/xorg"
EndSection

In `11-nvidia-prime.conf’:

# DO NOT EDIT. AUTOMATICALLY GENERATED BY gpu-manager

Section "OutputClass"
    Identifier "Nvidia Prime"
    MatchDriver "nvidia-drm"
    Driver "nvidia"
    Option "AllowEmptyInitialConfiguration"
    Option "IgnoreDisplayDevices" "CRT"
    Option "PrimaryGPU" "Yes"
    ModulePath "/lib/x86_64-linux-gnu/nvidia/xorg"
EndSection

In 10-amdgpu.conf:

Section "OutputClass"
    Identifier "AMDgpu"
    MatchDriver "amdgpu"
    Driver "amdgpu"
EndSection

I suppose something went wrong in these configurations?

Any help is greatly appreciated!


Get this bounty!!!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.