RadeonSI Gallium3D driver now has the support changes for Polaris, the Radeon Rx 400 series hardware being released soon. Plus related changes in the hardware enablement of these new GPUs.
It's great to see the code already hitting Mesa and will ensure it's in the Mesa 11.3/12.0 release due out this summer, but unfortunately not for the belated Mesa 11.2 release that should be imminent.
The Gallium3D driver changes for supporting Polaris aren't too invasive while the majority of the hardware bring-up is within the AMDGPU DRM kernel driver and that's not coming until the Linux 4.7 kernel cycle. The DAL prerequisite changes plus the Polaris kernel code amounts to over one hundred thousand lines of new code to be merged into Linux.