The "missing brightness level" problem can be worked around by using the kernel parameter video.brightness_switch_enabled=0.
Add the param to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub, then run 'sudo update-grub' and reboot.
The "missing brightness level" problem can be worked around by using the kernel parameter video.brightnes s_switch_ enabled= 0.
Add the param to GRUB_CMDLINE_ LINUX_DEFAULT in /etc/default/grub, then run 'sudo update-grub' and reboot.