Amd Ryzen 4800U and Ubuntu 20.04 external monitor

I got a new laptop with Amd Ryzen 4800U. Very happy and installed Ubuntu 20.04, everything looks right except it cannot detect the external monitor.

After investigate, the reason is current kernel(4.4) doesn’t support the video card intergated in Ryzen 4800U.
By default now(2020/10/23), Ubuntu 20.04 using kernel 4.4. You can not get newer kernel by sudo apt-get update && sudo apt-get upgrade.
You have to install manually. There is a wiki page for installing upstream kernels.

After installed packages bellow, the laptop is perfect now!
  amd64/linux-headers-5.9.0-050900-lowlatency_5.9.0-050900.202010112230_amd64.deb
  amd64/linux-headers-5.9.0-050900_5.9.0-050900.202010112230_all.deb
  amd64/linux-image-unsigned-5.9.0-050900-lowlatency_5.9.0-050900.202010112230_amd64.deb
  amd64/linux-modules-5.9.0-050900-lowlatency_5.9.0-050900.202010112230_amd64.deb