Aspire 5742 function button is screwy on Linux

ColPanekColPanek Member Posts: 3 New User
My son gave me this machine because it ran "upgraded" Windows 10 like a lame sloth. I've put Kubuntu and MX Linux on it and they both ran well, and we've used it to teach class over the internet. But I can't figure out how to adjust the screen brightness. There's a conflict between the brightness and screen ext/int functions; they both run at once. I've fooled with the keyboard settings endlessly, and fruitlessly. It's the blue "Fn" button that doesn't have the right driver, or something. Fn + any of the other F buttons doesn't work either.

FAQ & Answers

  • LeostatLeostat Member Posts: 376 Seasoned Practitioner
    X Backlight may allow you to change it from the command line. If the below works, you could always re map the function keys to run the commands from the keybaord settings. Janky yes, but it may work! :D
    sudo apt-get install xbacklight
    xbacklight -inc 10
    xbacklight -dec 10
    
    If you found the comment helpful hit the like button, If the answer solves your Q, hit the yes button on the bottom of the post! 
  • ColPanekColPanek Member Posts: 3 New User
    Excellent suggestion ... except no, it didn't work on my machine. The screen brightness isn't adjustable for some reason. All the buttons and sliders move, but the screen ignores it.
  • LeostatLeostat Member Posts: 376 Seasoned Practitioner
    Ahk! Does xbacklight -get give you  any info on the backlight? And do you have anything if you  ls /sys/class/backlight/
    If you found the comment helpful hit the like button, If the answer solves your Q, hit the yes button on the bottom of the post! 
  • ColPanekColPanek Member Posts: 3 New User
    Leostat said:
    Ahk! Does xbacklight -get give you  any info on the backlight? And do you have anything if you  ls /sys/class/backlight/

    $ xbacklight -get
    44.444444
     
    $ ls /sys/class/backlight/
    acpi_video0  intel_backlight

    More mysterious output:

    $ xbacklight -steps 6
    100.000000

    $ xbacklight -steps 20
    22.222222

    $ xbacklight -get
    22.222222

    $ xbacklight -steps 3
    33.333333

    $ xbacklight -steps 100
    44.44444

    But.... nothing changes the actual screen brightness, although the onscreen indicator says it is when I hit the up or down brightness


  • LeostatLeostat Member Posts: 376 Seasoned Practitioner
    edited January 14
    So from the ls what may be happening is xbacklight may be sending the brightness commands to the 'wrong' backlight as there is both an Intel and a Standard acpi device. My guess is the standard acpi is the graphics card, and the Intel is the igpu 

    You can echo a number into a file within the above directories directly to check if the distro is physically able to chnage the brightness, arch wiki to the rescue
    https://wiki.archlinux.org/index.php/backlight#ACPI

    You need to be root / sudo when you do, hopefully this works!

    Failing this, There is also a note where you may need to add a flag to the kernel to suppress the acpi device to be able to control the brightness
    If you found the comment helpful hit the like button, If the answer solves your Q, hit the yes button on the bottom of the post! 
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