In the first Radeon drm-next batch of changes the big work was on enabling open-source VCE video encode support. In the second drm-next pull for the Radeon driver the changes include better video RAM usage, a rework of the VM page table, support for different UVD clocks, and general clean-ups and improvements.
This second batch of changes for Linux 3.15 deal with less than 2,000 lines of code. The changes were sent in this morning by Christian König who is serving as the temporary Radeon DRM maintainer in place of Alex Deucher for the 3.15 release cycle. The changes are outlined in this mailing list post.