https://bugs.freedesktop.org/show_bug.cgi?id=67043
--- Comment #4 from Parag parag.warudkar@gmail.com --- Tried with radeon.dpm=0 on current mainline - no difference, still got the stuck message and delayed resume. Also tried with 3.8 Ubuntu stock kernel and 3.10.1 kernel from Ubunty daily mainline builds - the issue doesn't exist on both kernels. So it matches my vague memory that it started post 3.11 - unsure if that was after dpm or some other patchset prior to that.