AMD Posts New AMDGPU Patches For UVD Video Decode For GCN 1.0

One of the main blockers from AMD Radeon GCN 1.0 "Southern Islands" GPUs achieving feature parity when using the newer AMDGPU DRM kernel driver rather than the older "Radeon" DRM kernel driver has been in regards to UVD video decoding. But in 2020 it looks like that might finally change.

For years there have been experimental patches for UVD with GCN 1.0 on the AMDGPU driver albeit never merged and hasn't come up now in several years. But surprisingly today an AMD engineer posted new patches for bringing GCN 1.0 UVD support to AMDGPU.

This UVD 3.1 support for SI (Southern Islands) appears to be based on new code and in fact AMD carrying a 2020 copyright on the work.

The 7 patches end up enabling UVD support for AMD Radeon Oland, Verde, Tahiti, and Pitcairn GPUs for this newer driver. We'll see if these patches get queued eventually for hitting Linux 5.9 or later.

The GCN 1.0/1.1 support for the AMDGPU kernel driver has remained experimental and disabled by default due to missing functionality like the UVD bits. Using the AMDGPU kernel driver though can often yield better performance, is required for Vulkan API support, and in general receives more improvements/fixes/optimizations compared to the older Radeon DRM driver that is effectively deprecated in seldom seeing new commits. Switching from Radeon to AMDGPU can be done via the radeon.si_support=0 amdgpu.si_support=1 kernel module parameters.