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Christopher Hansen avatar Ubuntu

Cannot change brightness Ubuntu 22.10, Razer Blade 15 2021 Advanced

cy flag
Christopher Hansen

I have scoured the internet, but have not found a solution that works. I downloaded ubuntu for a machine learning workload. However, I am unable to get my brightness controls to work properly. The function keys on the keyboard will change the slider, and I can manually change the slider, but it does not change the brightness level. I cannot even change it using xrandr. I am using kernel 6.2.8, and nvidia-driver-515. (I tried 525, it did not work either.) Any help is appreciated; my eyes are burning.

Ok, some updates after investigation: When the function keys or slider tries to change the brightness, it changes the value in /sys/class/backlight/nvidia_wmi_ec_backlight/brightness file. However, I can manually change the brightness by changing the value in the /sys/class/backlight/nvidia_0/brightness file. It seems the discrepancy is basically getting the gui/function keys to change the value in the nvidia_0/brightness file, not the nvidia_wmi_ec_backlight/brightness file. I am not sure on how to do that.

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matigo
From what I have seen over the last few years, most Razer notebooks cannot have their brightness levels changed without a very specific utility that works only in Windows. If you have an OLED display, [this ICC profile *may* help](https://github.com/udifuchs/icc-brightness), but there is no guarantee. Do note that `xrandr` will not work if you're using a Wayland session, which is default for 22.10
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Christopher Hansen avatar
cy flag
Christopher Hansen
I was able to use this command to change the brightness to 50%: sudo su -c "echo 50 > /sys/class/backlight/nvidia_0/brightness" However, this is tedious, and was hoping that I could find a way to link the gui slider and function buttons to it
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matigo
One option would be to use an `inotify` watcher that updates the correct value when the wrong setting is updated
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Christopher Hansen avatar Ubuntu
cy flag
Christopher Hansen

Ok, I figured out a fix. I will document it here for future reference in case I need to rebuild my machine, or if someone else has this issue.

  1. Create the following script: (I called it /home/user/brightness.sh)

    #!/bin/bash path=/sys/class/backlight/nvidia_wmi_ec_backlight inotifywait -q -m -e close_write $path | while read -r event; do
    actual_brightness=$(cat $path/brightness)
    scaled_brightness=$(echo "scale=0; (($actual_brightness - 5) * 99) / (255 - 5) + 1" | bc)
    echo "Actual brightness: $actual_brightness, scaled brightness: $scaled_brightness"
    echo $scaled_brightness > /sys/class/backlight/nvidia_0/brightness || echo "Failed to write brightness: $?" done

  2. Allow this script to run with sudo and not require a password. This is fairly simple to do; use this site as a reference: https://www.cyberciti.biz/faq/linux-unix-running-sudo-command-without-a-password/. Or just ask chatgpt.

  3. Add this script to the startup applications as a command. Ex: add the command: sudo /bin/bash /home/user/brightness.sh to run at startup.

I also had an issue with the trackpad not working after waking the machine back up from suspend. I fixed this by following the directions here: Razer Blade 15 Errors on new ubuntu 22 installation ACPI BIOS Error (bug) + trackpad not working after suspending

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