+/**
+ * Find one BSD ring to dispatch the corresponding BSD command.
+ * The Ring ID is returned.
+ */
+static int gen8_dispatch_bsd_ring(struct drm_device *dev,
+ struct drm_file *file)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct drm_i915_file_private *file_priv = file->driver_priv;
+
+ /* Check whether the file_priv is using one ring */
+ if (file_priv->bsd_ring)
+ return file_priv->bsd_ring->id;
+ else {
+ /* If no, use the ping-pong mechanism to select one ring */
+ int ring_id;
+
+ mutex_lock(&dev->struct_mutex);
+ if (dev_priv->ring_index == 0) {
+ ring_id = VCS;
+ dev_priv->ring_index = 1;
+ } else {
+ ring_id = VCS2;
+ dev_priv->ring_index = 0;
+ }
+ file_priv->bsd_ring = &dev_priv->ring[ring_id];
+ mutex_unlock(&dev->struct_mutex);
+ return ring_id;
+ }
+}
+