Access to VSYNC?

Olli Mannisto

After some googling around, it seems VSYNC and ability to detect VSYNC is something of a trail of tears in Linux..

Kernel 4.9 does include Linux media infrastructure userspace API which does have a function capable of detecting VSYNC:
https://www.kernel.org/doc/html/v4.9/media/uapi/v4l/vidioc-dqevent.html

Is this actually implemented in UP^2? Is it in any way useful on X anyways e.g. wait for VSYNC and update your frame buffer.