drm/i915: reuse i915_gem_object_put_fence_reg for fence stealing code

This has a few functional changes against the old code:

* a few more unnecessary loads and stores to the drm_i915_fence_reg
  objects. Also an unnecessary store to the hw fence register.

* zaps any userspace mappings before doing other flushes. Only changes
  anything when userspace does racy stuff against itself.

* also flush GTT domain. This is a noop, but still try to keep the
  bookkeeping correct.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c73da40..302e096 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2460,39 +2460,16 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
                         */
                        drm_gem_object_reference(old_obj);
 
-                       /* i915 uses fences for GPU access to tiled buffers */
-                       if (IS_I965G(dev) || !old_obj_priv->active)
-                               break;
-
-                       /* This brings the object to the head of the LRU if it
-                        * had been written to.  The only way this should
-                        * result in us waiting longer than the expected
-                        * optimal amount of time is if there was a
-                        * fence-using buffer later that was read-only.
-                        */
-                       i915_gem_object_flush_gpu_write_domain(old_obj);
-                       ret = i915_gem_object_wait_rendering(old_obj);
-                       if (ret != 0) {
-                               drm_gem_object_unreference(old_obj);
-                               return ret;
-                       }
-
                        break;
                }
 
-               /*
-                * Zap this virtual mapping so we can set up a fence again
-                * for this object next time we need it.
-                */
-               i915_gem_release_mmap(old_obj);
-
                i = old_obj_priv->fence_reg;
                reg = &dev_priv->fence_regs[i];
 
-               old_obj_priv->fence_reg = I915_FENCE_REG_NONE;
-               list_del_init(&old_obj_priv->fence_list);
-
+               ret = i915_gem_object_put_fence_reg(old_obj);
                drm_gem_object_unreference(old_obj);
+               if (ret != 0) 
+                       return ret;
        }
 
        obj_priv->fence_reg = i;