media: mc: Fix graph walk in media_pipeline_start

The graph walk tries to follow all links, even if they are not between
pads. This causes a crash with, e.g. a MEDIA_LNK_FL_ANCILLARY_LINK link.

Fix this by allowing the walk to proceed only for MEDIA_LNK_FL_DATA_LINK
links.

Signed-off-by: Tomi Valkeinen <[e-mail]>
Cc: [e-mail] # for 6.1 and later
Fixes: ae219872834a ("media: mc: entity: Rewrite media_pipeline_start()")
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/mc/mc-entity.c

···
 	link = list_entry(entry->links, typeof(*link), list);
 	last_link = media_pipeline_walk_pop(walk);
 
+	if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) != MEDIA_LNK_FL_DATA_LINK) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (not data-link)\n");
+		return 0;
+	}
+
 	dev_dbg(walk->mdev->dev,
 		"media pipeline: exploring link '%s':%u -> '%s':%u\n",
 		link->source->entity->name, link->source->index,