Linux 3.14 Radeon DRM changes were already submitted to drm-next, which includes improved DRM support and various other changes, particularly for the newer AMD GPUs. This latest Radeon DRM pull that was sent in today provides additional fixes.
This newest pull request incorporates ten fixes from Alex Deucher and Christian König. It's not too much of a big deal unless you were impacted by one of the bugs, which is listed with this mailing list message.
Stay tuned for Radeon DRM (and other graphics driver) benchmarks from Linux 3.14 in the next few weeks but for now you can check out this week's 25-way open-source GPU comparison and read about other Linux 3.14 features.