[PATCH 0/3] Add (internal) MESA_query_timestamp extension to anv/radv

This extension fetches the current GPU timestamp from the hardware, just like the OpenGL API glGetInteger64v(GL_TIMESTAMP, &timestamp) function.

I need this to correlate GPU and CPU timestamps for the GOOGLE_display_timing extension, but I think it will be useful for applications as well.

I'm not sure this is exactly the API we need for this; it might be better for it to return *two* timestamps, a GPU and a CPU one which were as closely correlated as possible down in the kernel.

The kernel APIs that this calls on anv and radv don't do that, so I didn't want to pretend to offer functionality I couldn't actually supply.

Suggestions on what to do here are welcome!

-keith