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

3 files changed, 15 insertions, 11 deletions

diff --git a/mpm/python/usrp_mpm/dboard_manager/eiscat.py b/mpm/python/usrp_mpm/dboard_manager/eiscat.py
index 6997e2fc9..b3d70673d 100644
--- a/mpm/python/usrp_mpm/dboard_manager/eiscat.py
+++ b/mpm/python/usrp_mpm/dboard_manager/eiscat.py
@@ -35,7 +35,7 @@ def create_spidev_iface_sane(dev_node):
     Create a regs iface from a spidev node (sane values)
     """
     return lib.spi.make_spidev_regs_iface(
-        dev_node,
+        str(dev_node),
         1000000, # Speed (Hz)
         3, # SPI mode
         8, # Addr shift
@@ -49,7 +49,7 @@ def create_spidev_iface_phasedac(dev_node):
     Create a regs iface from a spidev node (ADS5681)
     """
     return lib.spi.make_spidev_regs_iface(
-        dev_node,
+        str(dev_node),
         1000000, # Speed (Hz)
         1, # SPI mode
         20, # Addr shift
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")
+    ]
 
diff --git a/mpm/python/usrp_mpm/sysfs_gpio.py b/mpm/python/usrp_mpm/sysfs_gpio.py
index 6473d87ee..ea423dc00 100644
--- a/mpm/python/usrp_mpm/sysfs_gpio.py
+++ b/mpm/python/usrp_mpm/sysfs_gpio.py
@@ -19,7 +19,6 @@ Access to GPIOs mapped into the PS via sysfs
 """
 
 import os
-from builtins import range
 from builtins import object
 import pyudev
 from .mpmlog import get_logger
@@ -35,11 +34,11 @@ def get_all_gpio_devs():
     """
     try:
         context = pyudev.Context()
-        gpios = [device.sys_name.encode('ascii')
+        gpios = [device.sys_name
                  for device in context.list_devices(subsystem="gpio")
                  if os.path.exists(os.path.join( # udev probably has better ways to do this
                      GPIO_SYSFS_BASE_DIR,
-                     device.sys_name.encode('ascii'),
+                     device.sys_name,
                      GPIO_SYSFS_LABELFILE
                  ))
                 ]