For AMD Users, Linux 4.2 Will Bring The New AMDGPU Driver & VCE1 For Radeon
First off, the new AMDGPU kernel DRM driver for supporting all future AMD GPUs (Carrizo, Fiji, etc; along with the current Radeon R9 285 / Tonga) will be coming to the Linux 4.2 kernel. However, the AMDGPU kernel driver will be filed as a separate pull request next week. It was one month ago that AMD published the code to this new kernel driver along with the necessary changes to the Mesa/Gallium3D RadeonSI code and other user-space changes. It's this driver that will likely be used by the potential new Catalyst Linux driver model where the binary blob is limited to user-space.
In terms of changes to the existing Radeon DRM driver for Linux 4.2, it's not too compelling. The main change with Radeon for Linux 4.2 is the open-source VCE1 video encoding support. In AMD's earlier VCE video encoding support, the VCE 1.0 hardware wasn't supported for GPU-based video encoding. The VCE 1.0 block is found on AMD's Trinity and Richland APUs along with Tahiti, Pitcairn, Verge, Orland, and Arbua graphics cards.
The rest of the Radeon DRM changes for Linux 4.2 amount to bug fixes and code clean-ups. One interesting small change is there's now a GPU reset counter that can be queried by user-space.
More details via the DRI-devel message for pulling this new Radeon DRM code into DRM-Next.