I was facing this same issue on archlinux on my Ryzen 7 Omen 15, which has AMD Renoir integrated GPU with NVIDIA RTX 2060 discrete GPU:
OS: Arch Linux [x86_64]
Host: OMEN Laptop 15-en0xxx
Kernel: 5.17.5-arch1-1
Resolution: 2560x1440 @ 144Hz
DE: KDE Plasma 5.24.4
WM: KWin (X11)
CPU: AMD Ryzen 7 4800H with Radeon Graphics (16) @ 2.9GHz
GPU 1: AMD ATI Renoir
GPU 2: Nvidia GeForce RTX 2060 Mobile
Monitor was not working, tried
nvidia-xconfig
Then the monitor worked but the display didn't work. Switched to another tty, and removed xorg.conf
sudo rm /etc/X11/xorg.conf
to make it work again, but then again the monitor did not work.
Finally tried optimus-manager, worked like a charm! Just follow the instructions on the github README, they're pretty good (So good that the arch wiki points to them)
Still, for completion, here's what I did:
- Install optimus-manager using AUR
- Ensure the xorg.conf generated by running nvidia-xconfig is removed & reboot
- Install optimus-manager-qt (setting _with_plasma=true in the PKGBUILD as I'm using KDE Plasma)
- Run optimus-manager-qt in terminal, select Nvidia GPU from the tray icon
- It logs-out and logs back in and voila! Display on both built-in monitor & external monitor!
Now the built-in KDE display configurations on pressing the button on my laptop keyboard also work!