Created attachment 133476 [details]
dmesg crash log

I get random GPU lockups in Unigine Valley. Sometimes it happens at Test 5 and sometimes in Test 9. Basically the screen is freezing but music continues playing. After sometime there is only noise on the screen. The performance went also down, I saw 57 fps in Test 1 and now only 54 fps.
I also experience something similar during playing Shadow Warrior, in the Prologue mission, GPU hangs forever.

Bisected this to:
064550238ef0b44e341b2a50c3147f83c2a6d5b0 is the first bad commit
commit 064550238ef0b44e341b2a50c3147f83c2a6d5b0
Author: Marek Olšák <marek.olsak@amd.com>
Date:   Thu Jul 27 02:40:34 2017 +0200

    radeonsi: use CLEAR_STATE to initialize some registers
    
    Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

:040000 040000 621668e602ccd2f36299e329b096586baa920ba0 68d43945fde8fbbfad6ae444546a981af2507b03 M	src

During regression testing I faced https://bugs.freedesktop.org/show_bug.cgi?id=101969 where I saw some serious corruption of the graphics in Valley so I used this patch to overcome https://cgit.freedesktop.org/mesa/mesa/commit/?id=b9fc9d3f241758ed8a274be7abf68bf448653508 But its the same issue like in the bug report mentioned above. Seems the patch hasnt fixed all issues.

Device: AMD TAHITI (DRM 2.50.0 / 4.11.0-1-amd-staging, LLVM 5.0.0) (0x6798)
Radeon HD 7970