drm/i915: Provide a cheap ggtt vma lookup

"We do fairly often lookup the ggtt vma for an obj." - Chris Wilson. As
such, provide a function to offer slightly cheaper access to the vma.
Not performance tested. By my quick estimation it saves at least 3
pointer dereferences from the existing mechanism.

This patch mostly matches code from Chris in
<20130911221430.GB7825@nuc-i3427.alporthouse.com>

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 662c0ff..a3d43b2 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2030,6 +2030,9 @@ struct i915_vma *i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
 struct i915_vma *
 i915_gem_obj_lookup_or_create_vma(struct drm_i915_gem_object *obj,
                                  struct i915_address_space *vm);
+
+struct i915_vma *i915_gem_obj_to_ggtt(struct drm_i915_gem_object *obj);
+
 /* Some GGTT VM helpers */
 #define obj_to_ggtt(obj) \
        (&((struct drm_i915_private *)(obj)->base.dev->dev_private)->gtt.base)
@@ -2066,7 +2069,6 @@ i915_gem_obj_ggtt_pin(struct drm_i915_gem_object *obj,
        return i915_gem_object_pin(obj, obj_to_ggtt(obj), alignment,
                                   map_and_fenceable, nonblocking);
 }
-#undef obj_to_ggtt
 
 /* i915_gem_context.c */
 void i915_gem_context_init(struct drm_device *dev);

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 96ad99c..0d6b012 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3410,8 +3410,7 @@ i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
 
        /* And bump the LRU for this access */
        if (i915_gem_object_is_inactive(obj)) {
-               struct i915_vma *vma = i915_gem_obj_to_vma(obj,
-                                                          &dev_priv->gtt.base);
+               struct i915_vma *vma = i915_gem_obj_to_ggtt(obj);
                if (vma)
                        list_move_tail(&vma->mm_list,
                                       &dev_priv->gtt.base.inactive_list);
@@ -4972,3 +4971,17 @@ i915_gem_inactive_scan(struct shrinker *shrinker, struct shrink_control *sc)
                mutex_unlock(&dev->struct_mutex);
        return freed;
 }
+
+struct i915_vma *i915_gem_obj_to_ggtt(struct drm_i915_gem_object *obj)
+{
+       struct i915_vma *vma;
+
+       if (WARN_ON(list_empty(&obj->vma_list)))
+               return NULL;
+
+       vma = list_first_entry(&obj->vma_list, typeof(*vma), vma_link);
+       if (WARN_ON(vma->vm != obj_to_ggtt(obj)))
+               return NULL;
+
+       return vma;
+}