More Radeon RDNA3 Enablement, SubVP Feature Added To AMDGPU For Linux 5.20

Written by Michael Larabel in Radeon on 14 July 2022 at 07:15 PM EDT. 4 Comments
A final batch of feature updates for the AMDGPU/AMDKFD drivers were mailed in this afternoon to DRM-Next for queuing ahead of the Linux 5.20 merge window opening later this month.

Already in DRM-Next for Linux 5.20 is continued preparations for RDNA3 and the next-gen AMD CDNA-based Instinct accelerators. Though with their new hardware enablement approach it's all being done on a block-by-block basis and less clear to see the overall support state compared to the prior days of Linux driver patches coming under colorful fishy codenames.

The hope -- but without any official confirmation -- is that Linux 5.20's support will be "good enough" for at least the Radeon RX 7000 "RDNA3" graphics cards to be launched later this year. But at this stage it's just a hope and expectation based on the timing of the kernel cycles and how it plays out with Linux distributions... If RDNA3 isn't good to go with Linux 5.20 for at-launch support, it will be a bummer and mean any early customers will likely need to be spinning their own kernel builds with the latest patches or relying on third-party kernel builds, etc.

Sent in today as a last feature pull to DRM-Next ahead of the cut-off for Linux 5.20 material were more AMDGPU kernel driver changes in preparation for new hardware. There are updates for the Display Core Next (DCN) v3.2 block, DCN 3.1.4 support, SMU13 updates, soft-reset handling for GFX11 (RDNA3) graphics, and soft-reset handling for the SDMA 6 block. The soft-reset handling support for GFX11 is particularly useful in case of hangs.

Also as part of today's pull are fixes for DisplayPort Multi-Stream Transport (DP MST), audio fixes, adjusting the GART size on newer APUs for Scatter/Gather display support, GFXOFF status querying for VanGogh APUs, improved buffer object domain pinning, and some AMDKFD changes too.

This pull also notes of "DC SubVP support" being added. This "SubVP" feature for Display Core (DC) is for Sub Viewport functionality, based on the code patches enabling SubVP. This Sub Viewport feature appears to be a new DCN 3.2 hardware feature but the code or commit messages don't elaborate all of the capabilities of this SubVP functionality.

The pull outlining all of these remaining AMDGPU/AMDKFD changes geared for Linux 5.20 can be found via this pull request.
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