(In reply to Mauro Carvalho Chehab from comment #5)
> Created attachment 141526 [details]
> Dmesg with Kernel 4.18.0 vanilla

Forgot to mention, but the bug also happens on 4.18.0 vanilla.
So, the bug is somewhere between drm-next-2018-06-06-1, e. g.

between this changeset:

commit 568cf2e6aa0c762f14d2d0d481a006f93c63ab7a
Merge: 74860cbfdd41 ebe1d22b57b8
Author: Dave Airlie <airlied@redhat.com>
Date:   Wed May 30 11:06:17 2018 +1000

    Merge tag 'drm-amdkfd-next-2018-05-28' of
git://people.freedesktop.org/~gabbayo/linux into drm-next

    - Build amdkfd's related files inside amdgpu only if amdkfd is built
    - Fix compile warning
    - Print info message in case ASIC is not supported by amdkfd

    Signed-off-by: Dave Airlie <airlied@redhat.com>
    Link:
https://patchwork.freedesktop.org/patch/msgid/20180528110435.GA17960@odedg-x270

and Kernel 4.18.