mpm: Removed gratuitous encode(), safer udev lookups

- Udev lookups now just return empty lists when they can't find anything
- Made SPI dev interface factory Py2/3 safe

1 files changed, 11 insertions, 6 deletions

diff --git a/mpm/python/usrp_mpm/periph_manager/udev.py b/mpm/python/usrp_mpm/periph_manager/udev.py
index cb3b35a66..33cb3367a 100644
--- a/mpm/python/usrp_mpm/periph_manager/udev.py
+++ b/mpm/python/usrp_mpm/periph_manager/udev.py
@@ -21,27 +21,32 @@ from ..mpmlog import get_logger
 
 def get_eeprom_paths(address):
     """
-    Return EEPROM device paths for a given I2C address
+    Return list of EEPROM device paths for a given I2C address.
+    If no device paths are found, an empty list is returned.
     """
     context = pyudev.Context()
     parent = pyudev.Device.from_name(context, "platform", address)
     paths = [d.device_node if d.device_node is not None else d.sys_path
              for d in context.list_devices(parent=parent, subsystem="nvmem")]
+    if len(paths) == 0:
+        return []
     # We need to sort this so 9-0050 comes before 10-0050 (etc.)
     maxlen = max((len(os.path.split(p)[1]) for p in paths))
     paths = sorted(
         paths,
         key=lambda x: "{:>0{maxlen}}".format(os.path.split(x)[1], maxlen=maxlen)
     )
-    return [os.path.join(x.encode('ascii'), 'nvmem') for x in paths]
+    return [os.path.join(x, 'nvmem') for x in paths]
 
 def get_spidev_nodes(spi_master):
     """
-    Return found spidev device paths for a given SPI master
+    Return list of spidev device paths for a given SPI master. If no valid paths
+    can be found, an empty list is returned.
     """
     context = pyudev.Context()
     parent = pyudev.Device.from_name(context, "platform", spi_master)
-    paths = [device.device_node.encode('ascii')
-             for device in context.list_devices(parent=parent, subsystem="spidev")]
-    return paths
+    return [
+        device.device_node
+        for device in context.list_devices(parent=parent, subsystem="spidev")
+    ]