I am having Dell Vostro 2520 laptop. Recently, the brightness control shortcuts using Fn keys is not working. Although the volume control shortcuts are working perfectly fine. I assume this is due to some updates which I did available from the Software and Updates tool . As these brightness controls were working perfectly fine since the day I installed this distro 2 years back. I tried some of the solutions found on net like changing /etc/default/grub file with
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor". Earlier, it was "quiet splash nouveau.modeset=0" but it set the screen to full brightness which is not acceptable.
Note that, I do not have a Nvidia driver in my laptop.
Kindly advise me on this fix.