Hitting the web today are the AMDGPU kernel patches for the Polaris hardware. There are 52 kernel patches for their AMDGPU DRM driver to support graphics, UVD video decoding, VCE video encoding, power management, and display support for these next-generation GPUs. The patches were published by AMD's Alex Deucher.
The initial Baffin PCI IDs include 0x67E0, 0x67E1, 0x67E8, 0x67E9, 0x7EB, and 0x7FF. The Ellesmere IDs are 0x67C0 and 0x67DF.
This support for the yet-to-be-released Polaris GPUs is dependent upon the DAL display code that has yet to be mainlined. Polaris includes the ELLESMERE and BAFFIN chip families. It's great to see power management included in the initial support code and not being held off for later as was unfortunately the case with the earlier GCN hardware when bringing up the original AMDGPU driver.
It's too late for this Polaris support to be merged into Linux 4.6, so Linux 4.7 will be the next opportunity for the code to land. Hopefully it will be all reviewed and ready to merge by that time -- and that the DAL will be ready too since the early DAL open-source code was criticized by upstream developers.
The early AMDGPU Polaris patches can be found here. Polaris support adds more than 67,000 lines of code to the kernel.
Polaris is likely to be marketed as the Radeon Rx 400 series and will be manufactured on a 14nm FinFET process, the higher-end hardware has HBM2, and there will be HDMI 2.0a and DisplayPort 1.3 display support. Polaris hardware should be a big advancement when it comes to power efficiency over earlier Radeon GPUs. Polaris hardware should begin shipping by this summer.