media: v4l2-mem2mem.c: fix broken links

The topology that v4l2_m2m_register_media_controller() creates for a
processing block actually created a source-to-source link and a sink-to-sink
link instead of two source-to-sink links.

Unfortunately v4l2-compliance never checked for such bad links, so this
went unreported for quite some time.

Signed-off-by: Hans Verkuil <[email protected]>
Reported-by: Nicolas Dufresne <[email protected]>
Cc: <[email protected]>      # for v4.19 and up
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

Author: Hans Verkuil

drivers/media/v4l2-core/v4l2-mem2mem.c

@@ -880,12 +880,12 @@ int v4l2_m2m_register_media_controller(struct v4l2_m2m_dev *m2m_dev,
 		goto err_rel_entity1;
 
 	/* Connect the three entities */
-	ret = media_create_pad_link(m2m_dev->source, 0, &m2m_dev->proc, 1,
+	ret = media_create_pad_link(m2m_dev->source, 0, &m2m_dev->proc, 0,
 			MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
 	if (ret)
 		goto err_rel_entity2;
 
-	ret = media_create_pad_link(&m2m_dev->proc, 0, &m2m_dev->sink, 0,
+	ret = media_create_pad_link(&m2m_dev->proc, 1, &m2m_dev->sink, 0,
 			MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
 	if (ret)
 		goto err_rm_links0;