https://bugs.freedesktop.org/show_bug.cgi?id=66963
--- Comment #131 from Sergey orbitgray@ukr.net --- (In reply to comment #126)
That's a GPU lock up which may not be related to dpm. I recently fixed an alignment issue with command buffers that may fix these hangs for you. you'll need this patch for libdrm:
With latest mesa and libdrm from git it looks much better. (never got same issue since update; though maybe just lucky so far)