[RFC v2 5/8] drm/fence: add in-fences support

[Gustavo Padovan]

2016-04-28 Ville Syrjälä <ville.syrjala at linux.intel.com>:

> On Thu, Apr 28, 2016 at 07:43:16PM +0200, Daniel Vetter wrote:
> > On Thu, Apr 28, 2016 at 6:56 PM, Ville Syrjälä
> > <ville.syrjala at linux.intel.com> wrote:
> > >>  - better for tracing, can identify the buffer/fence promptly
> > >
> > > Can fences be reused somehow while still attached to a plane, or ever?
> > > That might cause some oddness if you, say, leave a fence attached to one
> > > plane and then do a modeset on another crtc perhaps which needs to turn
> > > the first crtc off+on to reconfigure something.
> > 
> > Fences auto-disappear of course and don't stick around when you
> > duplicate the drm_plane_state again. I still don't really get the real
> > concerns though ...
> 
> Properties that magically change values shouldn't exist IMO. I guess if
> you could have write-only properties or something it migth be sensible?

We can just not return FENCE_FD on get_props, that would make it
write-only.

	Gustavo