drm/i915: Fix current fb blocking for page flip

Block execbuffer for the fb to be flipped away, not the one that is to
be flipped in.

[ickle: rewritten for -next]
Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e031d82..990f065 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4991,9 +4991,7 @@ static void do_intel_finish_page_flip(struct drm_device *dev,
 
        spin_unlock_irqrestore(&dev->event_lock, flags);
 
-       obj_priv = to_intel_bo(work->pending_flip_obj);
-
-       /* Initial scanout buffer will have a 0 pending flip count */
+       obj_priv = to_intel_bo(work->old_fb_obj);
        atomic_clear_mask(1 << intel_crtc->plane,
                          &obj_priv->pending_flip.counter);
        if (atomic_read(&obj_priv->pending_flip) == 0)
@@ -5092,9 +5090,14 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
        if (ret)
                goto cleanup_objs;
 
-       obj_priv = to_intel_bo(obj);
-       atomic_add(1 << intel_crtc->plane, &obj_priv->pending_flip);
+       /* Block clients from rendering to the new back buffer until
+        * the flip occurs and the object is no longer visible.
+        */
+       atomic_add(1 << intel_crtc->plane,
+                  &to_intel_bo(work->old_fb_obj)->pending_flip);
+
        work->pending_flip_obj = obj;
+       obj_priv = to_intel_bo(obj);
 
        if (IS_GEN3(dev) || IS_GEN2(dev)) {
                u32 flip_mask;