Since I've upgraded to Linux 4.7, if I set the screen brightness to any value other than 100% (with either fn keys or gnome sliders) it starts flashing from the brightness level I've set (e.g. 50%) to 100% and back. It's a combination of both flash and smooth up and down continuous adjustments. I've tried with the kernel parameters suggested in the arch wiki and with acpi_backlight=video or acpi_backlight=vendor the backlight control does not work, whereas with acpi_backlight=native I have the same behavior as described above (flashing). Any ideas? This happens on a Dell XPS 13 (old ivybridge model).

Also, after issuing this command (I've found some suggestions to old similar problems), pressing the fn keys, the level (and the indicators) are stuck to 100%:

sudo chmod u-w /sys/class/backlight/intel_backlight/brightness

Downgrading to Linux 4.6.x fixes the issue. So it looks like it's a regression bug. Any workaround?


I have found a solution.

In BIOS settings disable the "Load Legacy Boot Options" settings under Boot menu.

I remember that setting was required to be enabled in order for the fn keys to work with kernel prior to 4.7. Now it's the opposite.

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