You may have noticed that even though the brightness icon is appearing on your screen, it’s not actually adjusting the brightness. Here’s how to fix it.
From command line, run the following:
sudo gedit /etc/default/grub
Add the following lines to the end of the file.
#For adjusting brightness on Yoga 13 acpi_blacklight=vendor
Save and close the file.
From terminal, run:
Finally, blacklist the other device:
sudo gedit /etc/modprobe.d/blacklist.conf
Add the following lines to the end of the file. Save and close it.
#For adjusting brightness on Yoga 13 blacklist ideapad_laptop
Now, save your work and reboot.