[RFC v2 8/8] drm: tegra: Add gr2d device

[Dave Airlie]

>
> Third would be having a firewall in 2D driver checking the stream and
> ensuring all registers that accept addresses are written by values
> derived from dmabufs. I haven't tried implementing this, but it'd
> involve a lookup table in kernel and CPU reading through the command
> stream. Offsets and sizes would also need to be validated. There would
> be a performance hit.

This is the standard mechanism, and what exynos does as well.

The per process VM method is also used as an extension to this on some hw.

Dave.