staging: sync: Optimize fence merges

If the two fences being merged contain sync_pts from the same timeline,
those two pts will be collapsed into a single pt representing the latter
of the two.

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rob Clark <robclark@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Erik Gilling <konkers@android.com>
[jstultz: Whitespace fixes]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index 2afbd69ab9f0ceb21cf0ca15df05585d7757c6bf..6cb7c883fad0f5ef88410379ee7601dc23365035 100644 (file)
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -312,6 +312,56 @@ static int sync_fence_copy_pts(struct sync_fence *dst, struct sync_fence *src)
        return 0;
 }
 
+static int sync_fence_merge_pts(struct sync_fence *dst, struct sync_fence *src)
+{
+       struct list_head *src_pos, *dst_pos, *n;
+
+       list_for_each(src_pos, &src->pt_list_head) {
+               struct sync_pt *src_pt =
+                       container_of(src_pos, struct sync_pt, pt_list);
+               bool collapsed = false;
+
+               list_for_each_safe(dst_pos, n, &dst->pt_list_head) {
+                       struct sync_pt *dst_pt =
+                               container_of(dst_pos, struct sync_pt, pt_list);
+                       /* collapse two sync_pts on the same timeline
+                        * to a single sync_pt that will signal at
+                        * the later of the two
+                        */
+                       if (dst_pt->parent == src_pt->parent) {
+                               if (dst_pt->parent->ops->compare(dst_pt, src_pt)
+                                                == -1) {
+                                       struct sync_pt *new_pt =
+                                               sync_pt_dup(src_pt);
+                                       if (new_pt == NULL)
+                                               return -ENOMEM;
+
+                                       new_pt->fence = dst;
+                                       list_replace(&dst_pt->pt_list,
+                                                    &new_pt->pt_list);
+                                       sync_pt_activate(new_pt);
+                                       sync_pt_free(dst_pt);
+                               }
+                               collapsed = true;
+                               break;
+                       }
+               }
+
+               if (!collapsed) {
+                       struct sync_pt *new_pt = sync_pt_dup(src_pt);
+
+                       if (new_pt == NULL)
+                               return -ENOMEM;
+
+                       new_pt->fence = dst;
+                       list_add(&new_pt->pt_list, &dst->pt_list_head);
+                       sync_pt_activate(new_pt);
+               }
+       }
+
+       return 0;
+}
+
 static void sync_fence_free_pts(struct sync_fence *fence)
 {
        struct list_head *pos, *n;
@@ -386,7 +436,7 @@ struct sync_fence *sync_fence_merge(const char *name,
        if (err < 0)
                goto err;
 
-       err = sync_fence_copy_pts(fence, b);
+       err = sync_fence_merge_pts(fence, b);
        if (err < 0)
                goto err;