mpmd: Device discovery fixes and cleanup

- Fixed issue where the "addr" device args was not honored
- Results returned by find only enumerate mgmt_addrs
- Explicitly require addr to be specified for RFNoC comms
- Cleaned up constants for mgmt_addr, addr and second_addr

Reviewed-by: Martin Braun <martin.braun@ettus.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/host/lib/usrp/mpmd/mpmd_xport_mgr.cpp b/host/lib/usrp/mpmd/mpmd_xport_mgr.cpp
index 0de832b34..0ca77c740 100644
--- a/host/lib/usrp/mpmd/mpmd_xport_mgr.cpp
+++ b/host/lib/usrp/mpmd/mpmd_xport_mgr.cpp
@@ -93,7 +93,9 @@ private:
             }
         }
 
-        throw uhd::runtime_error("Could not select a transport option!");
+        throw uhd::runtime_error("Could not select a transport option! "
+                "Either a transport hint was not specified or the specified "
+                "hint does not support communication with RFNoC blocks.");
     }
 
     //! Create an instance of an xport manager implementation