[libcamera-devel] [PATCH v4 3/9] libcamera: media_device: Handle ancillary links in populateLinks()

[Daniel Scally]

The populateLinks() function can't currently handle ancillary links
which causes an error to be thrown in process() when the MediaObject
cannot be cast to a MediaPad.

Add explicit handling for the different link types, creating either
pad-2-pad links or else storing the pointer to the ancillary device
MediaEntity in the ancillaryEntities_ member of the primary.

Signed-off-by: Daniel Scally <djrscally at gmail.com>
---

Changes in v4:

	- Added some error checking to confirm that the casts to pad or entity
	return valid pointers (Laurent)

Changes in v3:

	- Split out the new macro
	- Fixed some style errors and comments
	- Added a default case

 src/libcamera/media_device.cpp | 67 ++++++++++++++++++++++++++--------
 1 file changed, 51 insertions(+), 16 deletions(-)

diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
index 941f86c2..a008383a 100644
--- a/src/libcamera/media_device.cpp
+++ b/src/libcamera/media_device.cpp
@@ -683,40 +683,75 @@ bool MediaDevice::populateLinks(const struct media_v2_topology &topology)
 					   (topology.ptr_links);
 
 	for (unsigned int i = 0; i < topology.num_links; ++i) {
-		/* We only care about pad-2-pad links here. */
-		if ((mediaLinks[i].flags & MEDIA_LNK_FL_LINK_TYPE) !=
-		    MEDIA_LNK_FL_DATA_LINK)
+		/*
+		 * Skip links between entities and interfaces: interfaces are
+		 * not created as MediaObjects at this time, so the source and
+		 * sink pointers would never be found.
+		 */
+		if ((mediaLinks[i].flags & MEDIA_LNK_FL_LINK_TYPE) ==
+		    MEDIA_LNK_FL_INTERFACE_LINK)
 			continue;
 
-		/* Store references to source and sink pads in the link. */
+		/* Look up the source and sink objects. */
 		unsigned int source_id = mediaLinks[i].source_id;
-		MediaPad *source = dynamic_cast<MediaPad *>
-				   (object(source_id));
+		MediaObject *source = object(source_id);
 		if (!source) {
 			LOG(MediaDevice, Error)
-				<< "Failed to find pad with id: "
+				<< "Failed to find MediaObject with id: "
 				<< source_id;
 			return false;
 		}
 
 		unsigned int sink_id = mediaLinks[i].sink_id;
-		MediaPad *sink = dynamic_cast<MediaPad *>
-				 (object(sink_id));
+		MediaObject *sink = object(sink_id);
 		if (!sink) {
 			LOG(MediaDevice, Error)
-				<< "Failed to find pad with id: "
+				<< "Failed to find MediaObject with id: "
 				<< sink_id;
 			return false;
 		}
 
-		MediaLink *link = new MediaLink(&mediaLinks[i], source, sink);
-		if (!addObject(link)) {
-			delete link;
-			return false;
+		switch (mediaLinks[i].flags & MEDIA_LNK_FL_LINK_TYPE) {
+		case MEDIA_LNK_FL_DATA_LINK: {
+			MediaPad *sourcePad = dynamic_cast<MediaPad *>(source);
+			MediaPad *sinkPad = dynamic_cast<MediaPad *>(sink);
+			if (!source || !sink) {
+				LOG(MediaDevice, Error)
+					<< "Source or sink is not a pad";
+				return false;
+			}
+
+			MediaLink *link = new MediaLink(&mediaLinks[i],
+							sourcePad, sinkPad);
+			if (!addObject(link)) {
+				delete link;
+				return false;
+			}
+
+			link->source()->addLink(link);
+			link->sink()->addLink(link);
+
+			break;
+		}
+		case MEDIA_LNK_FL_ANCILLARY_LINK: {
+			MediaEntity *primary = dynamic_cast<MediaEntity *>(source);
+			MediaEntity *ancillary = dynamic_cast<MediaEntity *>(sink);
+			if (!primary || !ancillary) {
+				LOG(MediaDevice, Error)
+					<< "Source or sink is not an entity";
+				return false;
+			}
+
+			primary->addAncillaryEntity(ancillary);
+
+			break;
 		}
+		default:
+			LOG(MediaDevice, Warning)
+				<< "Unknown media link type";
 
-		source->addLink(link);
-		sink->addLink(link);
+			break;
+		}
 	}
 
 	return true;
-- 
2.25.1