drm: atmel-hlcdc: support asynchronous atomic commit operations

drm_atomic_helper_commit() does not support asynchronous commits.
Replace it by a specific commit function supporting these kind of requests.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
index fed517f..733dd1d 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
@@ -128,6 +128,7 @@
  * @planes: instantiated planes
  * @layers: active HLCDC layer
  * @wq: display controller workqueue
+ * @commit: used for async commit handling
  */
 struct atmel_hlcdc_dc {
 	const struct atmel_hlcdc_dc_desc *desc;
@@ -137,6 +138,10 @@
 	struct atmel_hlcdc_planes *planes;
 	struct atmel_hlcdc_layer *layers[ATMEL_HLCDC_MAX_LAYERS];
 	struct workqueue_struct *wq;
+	struct {
+		wait_queue_head_t wait;
+		bool pending;
+	} commit;
 };
 
 extern struct atmel_hlcdc_formats atmel_hlcdc_plane_rgb_formats;