Linux 4.9 Has Tear-Free PRIME Offloading Between Intel & AMDGPU
The drm/amdgpu: Attach exclusive fence to prime exported bo's. (v5) patch was merged fairly late into the Linux 4.9 kernel merge window.
The patch by Mario Kleiner explains, "External clients which import our bo's [buffer objects] wait only for exclusive dmabuf-fences, not on shared ones, ditto for bo's which we import from external providers and write to. Therefore attach exclusive fences on prime shared buffers if our exported buffer gets imported by an external client, or if we import a buffer from an external exporter... Prime export tested on Intel iGPU + AMD Tonga dGPU as DRI3/Present Prime render offload, and with the Tonga standalone as primary gpu."
This should allow for tear-free PRIME offloading on the multi-GPU systems with the Intel DRM driver and an AMDGPU-supported Radeon GPU. Further details via this bug report.