mpm: Detect number of liberio channels

Instead of using hard-coded values, detect the number of liberio
channels, and only offer liberio links if they exist.

2 files changed, 18 insertions, 5 deletions

diff --git a/mpm/python/usrp_mpm/periph_manager/e320.py b/mpm/python/usrp_mpm/periph_manager/e320.py
index 82185e51c..0343f7755 100644
--- a/mpm/python/usrp_mpm/periph_manager/e320.py
+++ b/mpm/python/usrp_mpm/periph_manager/e320.py
@@ -54,8 +54,7 @@ class E320XportMgrUDP(XportMgrUDP):
     }
 
 class E320XportMgrLiberio(XportMgrLiberio):
-    " E320-specific Liberio configuration "
-    max_chan = 6
+    "E320-specific liberio configuration"
 # pylint: enable=too-few-public-methods
 
 ###############################################################################
@@ -375,8 +374,10 @@ class e320(ZynqComponents, PeriphManagerBase):
         assert self.mboard_info['rpc_connection'] in ('remote', 'local')
         if self.mboard_info['rpc_connection'] == 'remote':
             return ["udp"]
-        # else:
-        return ["liberio"]
+        elif self._xport_mgrs["liberio"].max_chan > 0:
+            return ["liberio"]
+        else:
+            return ["udp"]
 
     def get_chdr_link_options(self, xport_type):
         """
diff --git a/mpm/python/usrp_mpm/xports/xportmgr_liberio.py b/mpm/python/usrp_mpm/xports/xportmgr_liberio.py
index f7c1861af..1b4f87fbf 100644
--- a/mpm/python/usrp_mpm/xports/xportmgr_liberio.py
+++ b/mpm/python/usrp_mpm/xports/xportmgr_liberio.py
@@ -8,6 +8,7 @@ Liberio Transport manager
 """
 
 from builtins import object
+import pyudev
 
 class XportMgrLiberio(object):
     """
@@ -18,8 +19,19 @@ class XportMgrLiberio(object):
     # Number of available DMA channels
     max_chan = 4
 
-    def __init__(self, log):
+    def __init__(self, log, max_chan=-1):
         self.log = log.getChild('Liberio')
+        if max_chan < 0:
+            context = pyudev.Context()
+            rx_of_nodes = list(context.list_devices(subsystem="platform",
+                OF_COMPATIBLE_0="ettus,usrp-rx-dma"))
+            tx_of_nodes = list(context.list_devices(subsystem="platform",
+                OF_COMPATIBLE_0="ettus,usrp-tx-dma"))
+            self.max_chan = min(len(rx_of_nodes), len(tx_of_nodes))
+            self.log.debug("Found {} channels".format(self.max_chan))
+        else:
+            self.max_chan = max_chan
+            self.log.debug("Reporting {} channels".format(self.max_chan))
 
     def init(self, args):
         """