[Intel-gfx] [PATCH 1/4] drm/i915: Pin fence for iomap

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-07-04 10:53:53)
> 
> On 03/07/2017 11:14, Chris Wilson wrote:
> > We probably want for the caller to specify whether the fence should be
> > pinned for their usage, but at the moment all callers do want the
> > associated fence, or none, so take it on their behalf.
> Wouldn't this be wasting fences for ring buffers?

No. We don't claim a fence unless used (the or none clause above). If
the object is untiled, like ringbuffers, we don't assign a fence. The
problem I'm thinking about for the future is having an iomap cached for
fenced and unfenced access, i.e. we need to track the type of iomap
similarly to regular vmaps.
-Chris