urces, and special
  ordering requirements (which differ even on the same platform
  sometimes for different outputs) there's no way we'd get this right
  for all cases. Especially since this is a under-used feature.
- And to top it off: On haswell even dp link re-training requires us
  to take down the entire display pipe - otherwise the chip dies.

So the only sane way is to do a full modeset on every crtc where the
output config changes in any way.

To support global modeset (i.e. set the configuration for all crtcs at
once) we'd then add one more function to allocate global and shared
objects in the best ways (e.g. fdi links, pch plls, ...). The crtc
functions would then simply use the pre-allocated stuff (and shouldn't
be able to fail, ever). We could even do all the object pinning in
there (and maybe try to defragment the global gtt if we fail)!

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
�=