With the experimental AMDGPU DRM driver's support for GCN 1.0 "Southern Islands" and GCN 1.1 "Sea Islands" graphics processors as an alternative to the default Radeon DRM driver, one of the disadvantages of that experimental kernel driver is losing out on UVD video decoding. But a port is in the works.

An independent Radeon user is trying to port the UVD video decoding kernel bits for GCN 1.0/1.1 from the Radeon DRM driver to AMDGPU. The code is not yet working and also requires an updated firmware blob image, but it appears he is making progress in the right direction.

The developer is being challenged by the lack of documentation around the video decode interfaces, but he is trying to push forward to get this UVD working for SI/CIK GPUs on the AMDGPU driver. The details in this mailing list thread.