Created attachment 131314 [details]
dmesg

I'm using the latest code from amd-staging-4.9 branch of ~agd5f/linux.

The screen locks are happening randomly when playing videos (in browser or with
mplayer) or when running commands that output a lot of text in xterm.
When it happens, contents of the screen are no longer refreshed, except for
mouse pointer.

Following errors are reported:

[drm:drm_atomic_helper_commit_cleanup_done] *ERROR* [CRTC:38:crtc-0] flip_done
timed out
[drm:dc_commit_surfaces] *ERROR* dm_dc_surface_commit: acrtc 0, already busy

My reproducer is to fill the screen with two xterm windows next to each other
and generate random lines of text in both of them, using command like this for
example:

tr -dc a-z1-4 </dev/urandom | tr 1-2 ' \n' | awk 'length==0 || length>50' | tr
3-4 ' ' | sed 's/^ *//' | cat -s | sed 's/ / /g' | fmt

It usually takes just a couple of minutes for the screen lock to happen.

I've bisected the issue to this commit:

https://cgit.freedesktop.org/~agd5f/linux/commit/?h=amd-staging-4.9&id=afbeb2d0961b2139bcf6553a710e6a8ae5d09d34