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I'm having the brightness issue, where screen brightness doesn't change, on a Lenovo Legion Y740 with Fedora 33 that I haven't been able to solve yet.

Here's the output of lspci | grep VGA:

00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630 (Mobile)
01:00.0 VGA compatible controller: NVIDIA Corporation TU106BM [GeForce RTX 2070 Mobile / Max-Q] (rev a1)

It defaults to the Intel graphics card.

Here's what my /etc/default/grub file looks like:

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 rhgb quiet acpi_backlight=video rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 intel.modeset=1"
GRUB_DISABLE_RECOVERY="true"
GRUB_ENABLE_BLSCFG=true

Here's some information that may be helpful.

I tried the suggestion the modify the grub file to change the acpi_backlight option. Before, the keyboard brightness keys didn't work at all. After changing to video, Fn + F6 or Fn + F7 make the window pop up that shows the bar for decreasing/increasing brightness, and the values change in the appropriate brightness file. However, brightness still does not change, this only turns the backlight off when I set brightness to 0.

I've also installed xbacklight, which doesn't work. I haven't debugged this yet, but when running xbacklight -dec 10, I get No outputs have backlight property, but I don't think this is the main issue.

I think the following two paragraphs may be indicative of the main issue.

When I find the file that holds the numerical value for brightness, in my case, this is /sys/class/backlight/acpi_video0/brightness/ when the Intel card is active, and I modify the value in place, the brightness doesn't change unless set to 0.

Next, on install I noticed that there are settings for /etc/X11/xorg.conf.d/ for the keyboard, in the file 00-keyboard.conf, but no settings for the backlight. What's the file I should put here? Is there any package I can install that would put the proper config file here?

I've installed appropriate intel and nvidia drivers.

Does any one have any idea what might be the issue?

Thank you in advance for any links, suggestions, or consideration.

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I ran into the same problem on a Lenovo Legion 5 15ARH05H. Two suggestions:

  • enter BIOS and enable switchable graphics (as opposed to discrete graphics). This solved the problem for me but from then on, I could not use a second screen via HDMI anymore, thus not an option.

  • use xrandr as seen on askubuntu. Determine your screen as follows:

$ xrandr --current
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1920x1080    144.10*+

In my case, my screen is DP-2 and I can change its brightness using xrandr --output DP-2 --brightness followed by a number between 0 and 1. Two drawbacks of this method:

  • the brightness keys are still not working
  • it does not work in combination with Night Light (reducing blue tones in the evening and during the night), or at least not that I am aware of.

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