[Intel-gfx] [PATCH 19/21] drm/i915: Enable the use of GPU semaphores whilst page-flipping

[Chris Wilson]

The 2D driver unfortunately uses the BLT ring in order to perform blits,
and will often blit between buffers in the course of a pageflip. (Though
usually it is from the post-flipped scanout to the window frontbuffer
for reasons known only to itself, maintaining the front buffer in case
of 2D access one presumes.)

As such, being able to use a GPU semaphore and not stall the CPU/GPU
whilst switching between rings for a pageflip is useful.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c |    8 +++-----
 1 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 801496a..fe45f4e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3217,11 +3217,9 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
 	if (ret)
 		return ret;
 
-	if (pipelined != obj->ring) {
-		ret = i915_gem_object_wait_rendering(obj);
-		if (ret)
-			return ret;
-	}
+	ret = i915_gem_object_move_to_ring(obj, pipelined);
+	if (ret)
+		return ret;
 
 	/* The display engine is not coherent with the LLC cache on gen6.  As
 	 * a result, we make sure that the pinning that is about to occur is
-- 
1.7.4.1