drm/i915: Simplify fence finding

As the fences are stored in LRU order, we can simply reuse the oldest if
we do not have an unused register.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b25d22971513a2b702d7bd6ca860abb0ba03511b..f7cd3461dc4f42892638cbbe67f9a47757bf9c6a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2352,7 +2352,7 @@ static struct drm_i915_fence_reg *
 i915_find_fence_reg(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
-       struct drm_i915_fence_reg *reg, *first, *avail;
+       struct drm_i915_fence_reg *reg, *avail;
        int i;
 
        /* First try to find a free reg */
@@ -2370,24 +2370,14 @@ i915_find_fence_reg(struct drm_device *dev)
                return NULL;
 
        /* None available, try to steal one or wait for a user to finish */
-       avail = first = NULL;
        list_for_each_entry(reg, &dev_priv->mm.fence_list, lru_list) {
                if (reg->pin_count)
                        continue;
 
-               if (first == NULL)
-                       first = reg;
-
-               if (reg->obj->last_fenced_seqno == 0) {
-                       avail = reg;
-                       break;
-               }
+               return reg;
        }
 
-       if (avail == NULL)
-               avail = first;
-
-       return avail;
+       return NULL;
 }
 
 /**