I tried install this driver for RX 550
(https://drivers.amd.com/drivers/linux/amdgpu-pro-18.50-756341-ubuntu-18.04.tar.xz)
3 times and after installation the system doesn't begin, it just hold on a
black screen saying:

[  8.6668039] ccp 0000:08:00:02: sev command 0x4 timed out, disabling PSP
[  8.6668075] ccp 0000:08:00:02: SEV: failed to get status. Error: 0x0

In that screen system doesn't answer any command.
If I change to tty2 (ctrl+alt+f2) I could login on the terminal e do
amdgpu-uninstall and reboot (it works one time) and system would start
normally.

So I couldn't fix that I had to reinstall the hole system (Kubuntu).

Base-Board: GA-A320M-S2H
BIOS version: F24
CPU: Ryzen 5 2600
GPU: RX 550 4GT - MSI
RAM: 8Gb HyperX Fury
Font: Bluecase 500W