RFNoC: More graph traversal fixes

- Store number of input and ouptput ports from block definition.
- Use number of input and ouptut ports for graph traversal rather
  than number of connected blocks.
- Fixes DAC synchronization failure errors when using only one TX
  channel on X300.

Signed-off-by: michael-west <michael.west@ettus.com>

2 files changed, 31 insertions, 3 deletions

diff --git a/host/include/uhd/rfnoc/node_ctrl_base.hpp b/host/include/uhd/rfnoc/node_ctrl_base.hpp
index 0fed28bed..db552ff4c 100644
--- a/host/include/uhd/rfnoc/node_ctrl_base.hpp
+++ b/host/include/uhd/rfnoc/node_ctrl_base.hpp
@@ -166,11 +166,31 @@ public:
             get_property, null_value, exclude_nodes);
     }
 
+    UHD_INLINE size_t get_num_input_ports(void)
+    {
+      return _num_input_ports;
+    }
+
+    UHD_INLINE void set_num_input_ports(size_t num_ports)
+    {
+        _num_input_ports = num_ports;
+    }
+
+    UHD_INLINE size_t get_num_output_ports(void)
+    {
+      return _num_output_ports;
+    }
+
+    UHD_INLINE void set_num_output_ports(size_t num_ports)
+    {
+        _num_output_ports = num_ports;
+    }
+
 protected:
     /***********************************************************************
      * Structors
      **********************************************************************/
-    node_ctrl_base(void) {}
+    node_ctrl_base(void) : _num_input_ports(0), _num_output_ports(0) {}
     virtual ~node_ctrl_base()
     {
         disconnect();
@@ -263,6 +283,14 @@ private:
      */
     std::map<size_t, size_t> _downstream_ports;
 
+    /*! Stores the number of input ports.
+     */
+    size_t _num_input_ports;
+
+    /*! Stores the number of output ports.
+     */
+    size_t _num_output_ports;
+
 }; /* class node_ctrl_base */
 
 }} /* namespace uhd::rfnoc */
diff --git a/host/include/uhd/rfnoc/node_ctrl_base.ipp b/host/include/uhd/rfnoc/node_ctrl_base.ipp
index cb56e2d90..43a3cb162 100644
--- a/host/include/uhd/rfnoc/node_ctrl_base.ipp
+++ b/host/include/uhd/rfnoc/node_ctrl_base.ipp
@@ -85,8 +85,8 @@ namespace uhd {
                             // map each input port directly to the same output
                             // port.  This limits the graph traversal to prevent
                             // finding nodes that are not part of this chain.
-                            if (one_next_node->list_upstream_nodes().size() ==
-                                one_next_node->list_downstream_nodes().size())
+                            if (one_next_node->get_num_input_ports() ==
+                                one_next_node->get_num_output_ports())
                             {
                                 next_port = (downstream ?
                                     node->get_downstream_port(connected_port) :