AMD Preps For A Big Linux 4.20 Kernel With Vega 20, Picasso, Raven 2, xGMI, Better DC

Written by Michael Larabel in Radeon on 15 September 2018 at 06:47 AM EDT. 20 Comments
It was a busy Friday for the open-source AMD folks as in addition to releasing AMDGPU DDX 18.1 and the big ROCm 1.9 release, their latest batch of feature changes were also submitted to DRM-Next ahead of the Linux 4.20~5.0 kernel cycle. This is going to be another exciting release for Radeon Linux users.

There are a lot of new features and improvements to be found in this latest pull request that should appear in the DRM-Next tree. The work sent in by AMD's Alex Deucher includes:

- Initial support for the graphics on the yet-to-be-released Picasso APUs as well as Raven 2 APUs. AMD just open-sourced their AMDGPU bits for these new Vega/GFX9-based APUs earlier in the week.

- Continued work on bringing up the exciting Vega 20 that is expected to be out before year's end. It's looking like with this next kernel release the Vega 20 support will be all squared away and in good standing in time for the launch. It's widely anticipated this first Vega 20 GPU is a 7nm workstation product.

- Related to Vega 20 is AMDGPU now has initial xGMI support within the kernel driver. XGMI is a new interconnect that Vega 20 and future GPUs will support as an alternative to PCI Express 3.0/4.0.

- The AMDKFD code is merging into AMDGPU to be one kernel module.

- The seemingly never-ending work on power management continues with this cycle bringing ACP power-gating improvements and other changes.

- There is also a fair amount of display support including ABGR/XBGR support, DisplayPort YCbCr 4:2:0 support in the DC display code, LVDS support in the DC code, new debugfs features, and other work.

- Support for lightweight resetting of shaders via wave kill for GFX/Compute.

- VCN JPEG engine support for Raven Ridge APUs and newer. Also on the Raven front is DMCU firmware loading support.

- Raven Ridge APUs now also have GFXOFF support to turn off the graphics engine when not needed and stutter mode support.

- Support for load balancing within the AMDGPU/DRM scheduler and making use of that for the engine scheduling.

- GPUVM virtual memory performance improvements. There is also some GPUVM LRU handling efficiency enhancements. There is also some TTM fixes and support for bulk moves within that memory management code.

Overall, it's been a heck of a busy cycle for the AMD developers with prepping Vega 20 support and related features like xGMI, getting Raven2 and Picasso initial graphics support out there, still tweaking power management and AMDGPU DC, and working out other functionality. It's also still possible we could see another pull request or two of new feature material for this next kernel cycle with AMDGPU before the DRM-Next merge window is cut off in a few weeks.
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