Radeon R4 and kernel 4.19 (debian) freezes

[SledgeHammer_999]

I am on debian unstable. I have a laptop with Radeon R4 graphics.
When debian introduced the 4.19 kernel I keep having visual problems. In the first minor versions I couldn't get a GUI up. Now with 4.19.37 I can get into my DE (xfce) and launch eg a terminal window. But as soon as I launch firefox the screen freezes. The firefox window isn't drawn. No other GUI element works. Only the mouse cursor works/moves.
If I CTRL+ALT+F1 and then do CTRL+ALT+F7 the screen has drawn the firefox window, but again nothing moves/shows apart from the mouse cursor.
If I move the firefox window then go to CTRL+ALT+F1 and then back to CTRL+ALT+F7, I get the new UI update with the moved window.

Apparently something's up with the gpu driver/kernel interaction. It only paints stuff to the screen once I do a CTRL+ALT+F1 - CTRL+ALT+F7 cycle, and then it stops painting until my next cycle.

Also, when in CTRL+ALT+F1, if I use `sudo shutdown now` the system goes down (I hear no sound) but the power-led stays on and I get start the laptop again by the power button, unless I hold the power button down for a few seconds to actually poweroff the system. This doesn't happen with kernel 4.18 when I issue the above command.

Is this a known issue? Is there a config setting that I need to set?

PS: For the moment I am usign the 4.18 kernel which works fine.
PS1: With the 4.19 kernel lightdm/xfce are noticeably slower to appear on screen after the boot sequence.

[SledgeHammer_999]

I think it uses the amdgpu driver by default. Something else is up.
For example now I tried minimizing/unminimizing the firefox window (it is maximized to cover the whole screen). It did paint the changes from minimize/unminimize if I waited a few seconds. But have the time the window was half drawn with corrupted graphics. However, no interactio with the GUI elements was possible and the rest of the DE(eg the start menu) was unresponsive to mouse clicks.

[SledgeHammer_999]

dmesg | grep amdgpu

It does indeed have output about amdgpu


Anyway, as a crazy thought I installed kernel 5.0.2 from experimental. It works perfectly. So something's wrong with 4.19...
But since this is a machine I use every day, I am not gonna poke my system with 3rd party PPAs. I am going to wait for 5.0.x hitting debian unstable. Until then I'll do my job with 4.18.

I just had hoped that this was a known issue that could be resolved with a config setting.

[bluem0rpho]

I had the same issue running Kali linux 2019.2 (Kernel 4.19). Updating to Kernel 5 from Debian unstable addressed the display freeze issue.