i915_gem_object_get_fence — set up fencing for an object
int i915_gem_object_get_fence ( | struct drm_i915_gem_object * obj); |
When mapping objects through the GTT, userspace wants to be able to write
to them without having to worry about swizzling if the object is tiled.
This function walks the fence regs looking for a free one for obj,
stealing one if it can't find any.
It then sets up the reg based on the object's properties: address, pitch and tiling format.
For an untiled surface, this removes any existing fence.