drm/exynos: add async G2D execution to libdrm

[Tobias Jakobi]

Tobias Jakobi wrote:
> Hello,
> 
> this series exposes async execution of G2D command buffers to userspace. Also includes is a small performance analysis test, which can also be used to 
> stress test the engine. The async operation is of course also tested.
> 
> Please review and let me know what I can improve.
> 
> With best wishes,
> Tobias
Almost forgot this. In case someone is interested in the solid fill
performance, I've uploaded a plot here:
http://www.math.uni-bielefeld.de/~tjakobi/exynos/g2d_clear_perf.pdf

And yes, that should be _nano_seconds on the y-axis. What I find
interesting that despite the performance being linear (well, affine
linear, since we have a setup time) in the number of pixels to process,
you can still see some kind of 'clustering'.
I wonder where this comes from, maybe some small alignment penalty, or
something?

With best wishes,
Tobias