I can't adjust brightness

I've got a MSI GT72VR laptop with ONLY 1 graphic card, a NVIDIA GeForce GTX 1060 Mobile and 2 audio card, a NVIDIA GP106 and a Intel CM238.

The problem is that I can't adjust the brightness of my screen. Always is 100%. I've got Ubuntu 18.04 clean install and nouveau drivers (Xorg.org) enter image description here

There aren't brightness slider at the top of bar:

brightness slider

Also, the keys Fn + Bright Up and Fn + Bright Down doesn't do anything

Things I've already tried that don't work [1 May 2018]

  • Change driver to NVIDIA driver 390
  • Install and use redshift, xbacklight Link
  • Edit with sudo vi /etc/default/grub
    • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
    • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=native"
    • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=video"
    • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=off"
  • And then update-grub and reboot Link Link

Output for some commands

lspc | grep NVIDIA:

01:00.0 VGA compatible controller: NVIDIA Corporation GP106M [GeForce GTX 1060 Mobile] (rev a1) 
01:00.1 Audio device: NVIDIA Corporation GP106 High Definition Audio Controller (rev a1)

ll /sys/class/backlight:

total 0
drwxr-xr-x  2 root root 0 may  1 12:32 ./
drwxr-xr-x 67 root root 0 may  1 12:10 ../

dmesg | grep -i vga:

[    0.148024] pci 0000:01:00.0: vgaarb: setting as boot VGA device
[    0.148024] pci 0000:01:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
[    0.148024] pci 0000:01:00.0: vgaarb: bridge control possible
[    0.148024] vgaarb: loaded
[    0.969601] fb0: EFI VGA frame buffer device
[    1.349219] fb: switching to nouveaufb from EFI VGA
[  543.049571] snd_hda_intel 0000:01:00.1: Handle vga_switcheroo audio client

uname -a:

Linux laptop 4.15.0-20-generic #21-Ubuntu SMP Tue Apr 24 06:16:15 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

journalctl -b | grep -i nvidia:

may 01 12:19:27 laptop kernel: nouveau 0000:01:00.0: NVIDIA GP106 (136000a1)
may 01 12:19:28 laptop kernel: input: HDA NVidia HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input16
may 01 12:19:28 laptop kernel: input: HDA NVidia HDMI/DP,pcm=7 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input17
may 01 12:19:33 laptop /usr/lib/gdm3/gdm-x-session[1171]: (II) NOUVEAU driver for NVIDIA chipset families :
may 01 12:19:33 laptop /usr/lib/gdm3/gdm-x-session[1171]: (--) NOUVEAU(0): Chipset: "NVIDIA NV136"
may 01 12:19:38 laptop /usr/lib/gdm3/gdm-x-session[1171]: (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=3 (/dev/input/event15)
may 01 12:19:38 laptop /usr/lib/gdm3/gdm-x-session[1171]: (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=7 (/dev/input/event16)

inxi -SMCGAx:

System:    Host: laptop Kernel: 4.15.0-20-generic x86_64 bits: 64 gcc: 7.3.0
           Desktop: Gnome 3.28.1 (Gtk 3.22.30-1ubuntu1) Distro: Ubuntu 18.04 LTS
Machine:   Device: laptop System: Micro-Star product: GT72VR 7RD v: REV:1.0 serial: N/A
           Mobo: Micro-Star model: MS-1785 v: REV:1.0 serial: N/A
           UEFI: American Megatrends v: E1785IMS.30E date: 10/27/2017
CPU:       Quad core Intel Core i7-7700HQ (-MT-MCP-) arch: Skylake rev.9 cache: 6144 KB
           flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 22464
           clock speeds: max: 3800 MHz 1: 1046 MHz 2: 3165 MHz 3: 3164 MHz 4: 3139 MHz 5: 3093 MHz 6: 3190 MHz
           7: 3056 MHz 8: 3046 MHz
Graphics:  Card: NVIDIA GP106M [GeForce GTX 1060 Mobile] bus-ID: 01:00.0
           Display Server: x11 (X.Org 1.19.6 ) drivers: fbdev,nouveau (unloaded: modesetting,vesa)
           Resolution: 1920x1080@120.00hz
           OpenGL: renderer: NV136 version: 4.3 Mesa 18.0.0-rc5 Direct Render: Yes
Audio:     Card-1 Intel CM238 HD Audio Controller driver: snd_hda_intel bus-ID: 00:1f.3
           Card-2 NVIDIA GP106 High Definition Audio Controller driver: snd_hda_intel bus-ID: 01:00.1
           Sound: Advanced Linux Sound Architecture v: k4.15.0-20-generic

sudo lshw -C display:

       description: VGA compatible controller
       product: GP106M [GeForce GTX 1060 Mobile]
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller bus_master cap_list rom
       configuration: driver=nouveau latency=0
       resources: irq:131 memory:de000000-deffffff memory:c0000000-cfffffff memory:d0000000-d1ffffff ioport:e000(size=128) memory:c0000-dffff

2 Answers 2


I have an Asus GL502VM with Nvidia 1060 and a gsync display. I faced the same issue, haven't found a permanent fix but the workaround from here worked for me. In order to use it you need to install the nvidia driver instead of xorg one and modify the DP-0 value according to your setup, in my case according to xrandr --verbose my display is connected to DP-2 port. Also night light option will change the brightness level so I disabled it.

Brightness seems to be working in unity on 18.04 though.

The bug is reported https://bugs.launchpad.net/ubuntu/+bug/1767001


Try acpi_osi=

On upgrading to Bionic today, I encountered the same problem (same graphics card and the same problem with an empty /sys/class/backlight).

In working through the backlight debugging procedure, I discovered a workaround via kernel parameters. Mimicking your instructions above:

  • Change driver to NVIDIA driver 396.
  • Edit with sudo vi /etc/default/grub:
    • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi="
  • And then sudo update-grub and reboot.

(Bug reported here.)


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