qxl: add ring prep code for s/r

This prepare the ring code for s/r additions, the release ring will need
reinitialising.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/qxl/qxl_cmd.c

@@ -49,6 +49,11 @@ void qxl_ring_free(struct qxl_ring *ring)
 	kfree(ring);
 }
 
+void qxl_ring_init_hdr(struct qxl_ring *ring)
+{
+	ring->ring->header.notify_on_prod = ring->n_elements;
+}
+
 struct qxl_ring *
 qxl_ring_create(struct qxl_ring_header *header,
 		int element_size,
@@ -69,7 +74,7 @@ qxl_ring_create(struct qxl_ring_header *header,
 	ring->prod_notify = prod_notify;
 	ring->push_event = push_event;
 	if (set_prod_notify)
-		header->notify_on_prod = ring->n_elements;
+		qxl_ring_init_hdr(ring);
 	spin_lock_init(&ring->lock);
 	return ring;
 }
@@ -87,7 +92,7 @@ static int qxl_check_header(struct qxl_ring *ring)
 	return ret;
 }
 
-static int qxl_check_idle(struct qxl_ring *ring)
+int qxl_check_idle(struct qxl_ring *ring)
 {
 	int ret;
 	struct qxl_ring_header *header = &(ring->ring->header);

drivers/gpu/drm/qxl/qxl_drv.h

@@ -340,6 +340,8 @@ struct qxl_ring *qxl_ring_create(struct qxl_ring_header *header,
 				 bool set_prod_notify,
 				 wait_queue_head_t *push_event);
 void qxl_ring_free(struct qxl_ring *ring);
+void qxl_ring_init_hdr(struct qxl_ring *ring);
+int qxl_check_idle(struct qxl_ring *ring);
 
 static inline void *
 qxl_fb_virtual_address(struct qxl_device *qdev, unsigned long physical)