Ubuntu Screen brightness on Lenovo Legion Y540

Machine: Lenovo Legion Y540 Graphic: Nvidia GeForce GTX 1650
OS: Ubuntu 20.04

Symptom: screen brightness control is not working both from the slider or fn+F5 and fn+F6

Driver
I choose nvidia-driver-460-server as the graphic driver from Software & Updates; Additional Drivers

Solution 1:

Change the BIOS configuration from discrete graphic to switchable graphic.

Solution 2:

Run NVIDIA X Server Settings and click Save to X Configuration File

Save configuration file as /etc/X11/xorg.conf

Add the brightness control to /etc/X11/xorg.conf

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GTX 1650"
    Option    "RegistryDwords" "EnableBrightnessControl=1"
EndSection

save and reboot

If the above method is not working, try this one.

Edit /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=intel"

and then run sudo update-grub then reboot

The first solution should work right the way :)