drm/i915: Wait for vblank before unpinning old fb

Be paranoid and ensure that the vblank has passed and the scanout has
switched to the new fb, before unpinning the old one and possibly
tearing down its PTEs.

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 f2d50141e0c233f0eab6551d6938923a467f553e..840bfc3ae719d4ad6d609f7f4a577231e44b0b24 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1626,8 +1626,10 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
                return ret;
        }
 
-       if (old_fb)
+       if (old_fb) {
+               intel_wait_for_vblank(dev, intel_crtc->pipe);
                i915_gem_object_unpin(to_intel_framebuffer(old_fb)->obj);
+       }
 
        mutex_unlock(&dev->struct_mutex);