Brightness
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Secondary controller disabled
The secondary controller seem not not be adjustable, but the primary controller works well.

yes i am facing the same issue. Please someone help.
I tried this, and it worked
sudo gedit /etc/default/grub
Change the following line
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"
sudo update-grub
And reboot