Martin Babutzka has taken to maintaining a Linux kernel tree on GitHub with the latest AMDGPU DC/DAL patches pair with the latest upstream Linux kernel security patches, based upon the upstream Linux 4.9 kernel. He's carrying out this effort in order to make use of HDMI audio with his Radeon R9 380 graphics card.
Besides offering the source tree, he's also offering pre-built x86_64 Debian/Ubuntu packages of the said kernel.
Of course, try at your own risk, but an easy way to try out AMDGPU DC/DAL support for HDMI/DP audio on newer GPUs, HDMI 2.0 features, the start on atomic support, and other modern display features are sought out by many Phoronix readers.
His kernel tree can be found at M-Bab/linux-kernel-amdgpu and there is also the AMDGPU kernel binaries.
The AMDGPU DC/DAL code isn't being mainlined until the Linux 4.12 kernel at the earliest, thus the Ubuntu 17.04 release in April, which is using Linux 4.10, will still be without this display code.