[media] media: change pipeline validation return error

According to the V4L2 API, the VIDIOC_STREAMON ioctl should return EPIPE
if there is a format mismatch in the pipeline configuration.

As the .vidioc_streamon in the v4l2_ioctl_ops usually forwards the error
caused by the v4l2_subdev_link_validate_default (if it is in use), it
should return -EPIPE when it detect the mismatch.

When an entity is connected to a non enabled link,
media_entity_pipeline_start should return -ENOLINK, as the link does not
exist.
Signed-off-by: Helen Mae Koike Fornazier <helen.koike@collabora.co.uk>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-entity.c

@@ -445,7 +445,7 @@ __must_check int __media_entity_pipeline_start(struct media_entity *entity,
 		bitmap_or(active, active, has_no_links, entity->num_pads);
 
 		if (!bitmap_full(active, entity->num_pads)) {
-			ret = -EPIPE;
+			ret = -ENOLINK;
 			dev_dbg(entity->graph_obj.mdev->dev,
 				"\"%s\":%u must be connected by an enabled link\n",
 				entity->name,

drivers/media/v4l2-core/v4l2-subdev.c

@@ -510,7 +510,7 @@ int v4l2_subdev_link_validate_default(struct v4l2_subdev *sd,
 	if (source_fmt->format.width != sink_fmt->format.width
 	    || source_fmt->format.height != sink_fmt->format.height
 	    || source_fmt->format.code != sink_fmt->format.code)
-		return -EINVAL;
+		return -EPIPE;
 
 	/* The field order must match, or the sink field order must be NONE
 	 * to support interlaced hardware connected to bridges that support
@@ -518,7 +518,7 @@ int v4l2_subdev_link_validate_default(struct v4l2_subdev *sd,
 	 */
 	if (source_fmt->format.field != sink_fmt->format.field &&
 	    sink_fmt->format.field != V4L2_FIELD_NONE)
-		return -EINVAL;
+		return -EPIPE;
 
 	return 0;
 }