udmabuf synchronization
If we want to scan-out udmabufs straight to the display, we need write-combine buffers, which requires synchronization on the host. This task is to test and land some variation of:
https://lists.freedesktop.org/archives/dri-devel/2019-August/228874.html
The above patches depend on an implementation detail of the dma-mapping API. There are some patches under review to call expose architecture-specific helpers directly:
https://patchwork.freedesktop.org/series/65211/
We should wait until that settles down before attempting to land udmabuf sync.