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Linux 4.2 DRM Updates: Lots Of AMD Attention, No Nouveau Driver Changes
As expected, there's two new DRM drivers: AMDGPU and VirtIO. The widely sought after AMDGPU DRM driver is finally landing! This is the driver needed to support the AMD Radeon R9 285 "Tonga" and all future GPUs, including the Carrizo APUs and ultimately Fiji (but there's no Fiji / Fury X support yet). See the earlier Phoronix articles for more information. The VirtIO GPU driver is for providing a better out-of-the-box experience on QEMU/KVM and will ultimately be used with Red Hat's Virgil3D work, but that 3D acceleration support for guest VMs hasn't yet arrived.
Beyond the new AMDGPU driver, other new AMD work for the Linux 4.2 DRM merge window includes VCE1 video encode support, a GPU reset counter exposed to user-space, and many bug-fixes. The AMDKFD HSA driver has a hardware debugger support module, static user-mode queues, and various other changes.
The Intel DRM driver meanwhile adds the Intel Broxton Atom SoC support, more Skylake improvements, and many other changes.
The other driver updates include atomic mode-setting and IOMMU support for the Samsung Exynos DRM, atomic mode-setting for the OMAP DRM driver, Adreno A306 support in the Freedreno MSM driver, and various other fixes for the other smaller DRM drivers.
Within the core DRM code, the atomic mode-setting API is now considered complete! This new API is also now enabled by default and will lead to a better mode-setting experience moving forward with being able to test video modes before being applied and ideally leading to flicker-free experiences for properly-supported drivers. Core DRM code also has better DisplayPort MST (Multi-Stream Transport) handling.
As far as no Nouveau driver changes with Linux 4.2, David Airlie explained, "There is no major nouveau changes in here, Ben [Skeggs, Nouveau DRM maintainer] was working on something big, and we agreed it was a bit late, there wasn't anything else he considered urgent to merge."
The full list of all the DRM subsystem updates queued for the Linux 4.2 merge window can be found via Airlie's pull request. As always, benchmarks of the latest mainline daily Git code are done in a fully-automated fashion over at LinuxBenchmarking.com. Further benchmarks done covering specific feature changes in Linux 4.2 will be done in the weeks ahead as usual on Phoronix.