https://bugs.freedesktop.org/show_bug.cgi?id=94249
--- Comment #4 from Michel Dänzer michel@daenzer.net --- First of all, for Topaz / Iceland I think it's best to use current Git snapshots of Mesa and libdrm_amdgpu.
Please attach the full Xorg log corresponding to the failure.
A gdb backtrace would also be helpful, see https://www.x.org/wiki/Development/Documentation/ServerDebugging/ .