Plumbing explicit synchronization through the Linux ecosystem

[Tomek Bury]

>  As long as we can fall back to not using fences then we should be fine.
Buffers written by the camera are trivial because you control what
happens - just don't attach fence, so that the capture can be used
immediately. For recycled buffers there's an extra bit of work to do
because won't  be up to camera driver to decide whether the buffer
comes back with or without fence.