Clevo P950ER: can't set display brightness on Ubuntu 18.04

I installed Windows 10 and Ubuntu 18.04 on P950ER. On Windows Control Center driver and Intel GPU driver from Clevo (not Intel official) are required to change the display brightness. On Ubuntu I tried add "acpi_blacklight=vendor" and "acpi_osi=linux" to GRUB, but it doesn't work however I press Fn+F8/F9 trying to set the brightness. Any solution?

 

Try this string instead:
acpi_osi=! acpi_osi='Windows 2009'

And btw, no BIOSes (at present) respond to the ACPI_OSI=linux string.

Also, see this: https://gist.github.com/Brainiarc7/...335fd6#file-installing-linux-on-eurocom-q6-md

For any additional tweaks you may need (to get working audio, etc).

 

I installed Ubuntu with standard installer ("nomodeset" added to make it work) and followed the normal steps to get the drivers. The hardwares including audio jack seem working well, but the brightness of display can't be adjusted. Should I reinstall Ubuntu?

 

No need. Add these grub options mentioned above.

 

I did, but still can't. Is there any software else needed?

 

There's another way which involves passing a module option to the i915 driver.

Researching on this. Will be back with a solution.

Can you provide the output of:

ls -al /sys/class/backlight

 

Surely an Optimus laptop whose Nv GPU only works when gaming (on Windows). Appreciate it if you could provide another methods.
More info:
Serial No. NKP950ER0008E00268
BIOS Version 1.05.03.TBP

 

I'll do my best.

Please provide the output of:

ls -al /sys/class/backlight

 

:~$ ls -al /sys/class/backlight
total 0
drwxr-xr-x 2 root root 0 7月 12 23:23 .
drwxr-xr-x 70 root root 0 7月 13 2018 ..
lrwxrwxrwx 1 root root 0 7月 13 2018 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
lrwxrwxrwx 1 root root 0 7月 13 2018 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight

 

Beautiful, this means that we can use the intel_backlight method.

Here comes:

Can you run:

systemctl enable systemd-backlight@backlight:intel_backlight.service

And see what it returns?

 

:~$ systemctl enable systemd-backlight@backlight:intel_backlight.service
The unit files have no installation config (WantedBy, RequiredBy, Also, Alias
settings in the [Install] section, and DefaultInstance for template units).
This means they are not meant to be enabled using systemctl.
Possible reasons for having this kind of units are:
1) A unit may be statically enabled by being symlinked from another unit's
.wants/ or .requires/ directory.
2) A unit's purpose may be to act as a helper for some other unit which has
a requirement dependency on it.
3) A unit may be started when needed via activation (socket, path, timer,
D-Bus, udev, scripted systemctl call, ...).
4) In case of template units, the unit is meant to be enabled with some
instance name specified.

 

See this: https://help.ubuntu.com/community/ScreenBacklight

That script in there will help, especially with the intel_backlight method.

 

By default Openbox isn't installed on Ubuntu 18.04, I got it manually and did all the steps in the Wiki. After that, I ran sysbacklight up/down/set, but the brightness wasn't changed. The value of intel_backlight was modified, but no effect on display, nor do using Fn+F8/F9.

$ sudo sysbacklight set 0
$ cat /sys/class/backlight/intel_backlight/brightness
1

 

Sorry for the late reply, but try this:

We can confirm that your backlight driver is indeed intel_backlight, via the contents of:

ls /sys/class/backlight/


Here's how you can define the backlight driver for xorg to use:

Let's create a custom xorg conf file that won't be overwritten by Ubuntu's gpu-manager:

sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf

Then edit it as shown:

sudo nano /usr/share/X11/xorg.conf.d/20-intel.conf

With the content:

Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "intel_backlight"
BusID "PCI:0:2:0"
EndSection

Then log in and log out again.

PS: Be sure to confirm that the PCIID for your Intel HD Graphics controller matches the entry above (PCI:0:2:0).
Otherwise, change it to what your system reports.

Run this to confirm:

lspci -vnn | grep VGA -A 12