Hi, When I connect my Lenovo to external display by HDMI then I got a corruption. Desktop is split and the right part of the screen is lower by few pixels then the left part. Link: https://imgur.com/HXrg4iA Laptop: ThinkBook15-G2 with amdgpu_renoir, driver: drm-61-kmod-6.1.128.1402000_2 OS: 14.2-RELEASE-p3, kernel: 1402000.
AMDGPU is buggy in 14.2, please see bug 285747. Maybe the fix will work for you.