drm: Asynchronouse page flipping interface and Intel implementation

[Keith Packard]

Here's a sequence of five patches that exposes an interface to request
of the driver that the page flipping request be executed without
waiting for vblank. It's optional, and drivers can expose whether it
is supported through the existing GETCAP ioctl.

This supports only Ivybridge and Sandybridge Intel graphics chips as
that's what I've got to test on; of course all of the other drivers
have been modified so that they still compile cleanly.


--
keith.packard at intel.com