Hot answers tagged brightness
Ok! After a few days trying to sort out this issue, I found out that I had my ideapad_laptop module blacklisted on /etc/modprobe.d/blacklist.conf . It was due to a Bumblebee installation tutorial that I followed few days ago. So removing ideapad_laptop from my blacklist.conf solved the problem. Maybe one of the solutions I listed on the question works. So ...
On Dell Latitude laptops, the auto-brightness can be disabled in the BIOS. Reboot the computer and hold F2 before it starts. Look around in the menus for ALS or ambient light sensor. There you will be able to disable it.
Finally got the brightness controls to work properly! The issue persists due to presence of two backlight modules acpi_video0 and intel_backlight. You can cross check if both modules exists by running the below command. ls /sys/class/backlight/ If you find acpi_video0 as one of the modules run the command: sudo tee /sys/class/backlight/acpi_video0/...
I had to add these lines to grub: acpi_backlight=vendor acpi_osi=linux thinkpad-acpi.brightness_enable=1 Note that last one. That was the one that made the brightness keys work.
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