media: v4l2-mc: Add debug prints for v4l2_fwnode_create_links_for_pad()

Add relevant debug prints for v4l2_fwnode_create_links_for_pad(). This
should help debugging when things go wrong.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
index 52d349e..4bb9135 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-mc.c
+++ b/drivers/media/v4l2-core/v4l2-mc.c
@@ -337,12 +337,18 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
                src_idx = media_entity_get_fwnode_pad(&src_sd->entity,
                                                      endpoint,
                                                      MEDIA_PAD_FL_SOURCE);
-               if (src_idx < 0)
+               if (src_idx < 0) {
+                       dev_dbg(src_sd->dev, "no source pad found for %pfw\n",
+                               endpoint);
                        continue;
+               }
 
                remote_ep = fwnode_graph_get_remote_endpoint(endpoint);
-               if (!remote_ep)
+               if (!remote_ep) {
+                       dev_dbg(src_sd->dev, "no remote ep found for %pfw\n",
+                               endpoint);
                        continue;
+               }
 
                /*
                 * ask the sink to verify it owns the remote endpoint,
@@ -353,8 +359,12 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
                                                       MEDIA_PAD_FL_SINK);
                fwnode_handle_put(remote_ep);
 
-               if (sink_idx < 0 || sink_idx != sink->index)
+               if (sink_idx < 0 || sink_idx != sink->index) {
+                       dev_dbg(src_sd->dev,
+                               "sink pad index mismatch or error (is %d, expected %u)\n",
+                               sink_idx, sink->index);
                        continue;
+               }
 
                /*
                 * the source endpoint corresponds to one of its source pads,
@@ -367,8 +377,13 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
                src = &src_sd->entity.pads[src_idx];
 
                /* skip if link already exists */
-               if (media_entity_find_link(src, sink))
+               if (media_entity_find_link(src, sink)) {
+                       dev_dbg(src_sd->dev,
+                               "link %s:%d -> %s:%d already exists\n",
+                               src_sd->entity.name, src_idx,
+                               sink->entity->name, sink_idx);
                        continue;
+               }
 
                dev_dbg(src_sd->dev, "creating link %s:%d -> %s:%d\n",
                        src_sd->entity.name, src_idx,