udev: simplify find_paired_node

lib/hidapi/udev.py

@@ -38,6 +38,7 @@ from time import sleep
 from pyudev import Context as _Context
 from pyudev import Device as _Device
 from pyudev import DeviceNotFoundError
+from pyudev import Devices as _Devices
 from pyudev import Monitor as _Monitor
 
 native_implementation = 'udev'
@@ -48,7 +49,6 @@ DeviceInfo = namedtuple(
         'vendor_id',
         'product_id',
         'serial',
-        'phys',
         'release',
         'manufacturer',
         'product',
@@ -128,7 +128,6 @@ def _match(action, device, filter):
             path=device.device_node,
             vendor_id=vid[-4:],
             product_id=pid[-4:],
-            phys=hid_device.get('HID_PHYS'),
             serial=hid_device.get('HID_UNIQ'),
             release=attrs.get('bcdDevice'),
             manufacturer=attrs.get('manufacturer'),
@@ -145,7 +144,6 @@ def _match(action, device, filter):
             path=device.device_node,
             vendor_id=vid[-4:],
             product_id=pid[-4:],
-            phys=None,
             serial=None,
             release=None,
             manufacturer=None,
@@ -156,10 +154,18 @@ def _match(action, device, filter):
         return d_info
 
 
-def find_paired_node(receiver_phys, index):
-    for dev in _Context().list_devices(subsystem='hidraw'):
-        phys = dev.find_parent('hid').get('HID_PHYS')
-        if phys and '{}:{}'.format(receiver_phys, index) == phys:
+def find_paired_node(receiver_path, index):
+    """Find the node of a device paired with a receiver"""
+    context = _Context()
+    receiver_phys = _Devices.from_device_file(context, receiver_path).find_parent('hid').get('HID_PHYS')
+
+    if not receiver_phys:
+        return None
+
+    phys = f'{receiver_phys}:{index}'
+    for dev in context.list_devices(subsystem='hidraw'):
+        dev_phys = dev.find_parent('hid').get('HID_PHYS')
+        if dev_phys and dev_phys == phys:
             return dev.device_node
 
     return None

lib/logitech_receiver/device.py

@@ -128,7 +128,7 @@ class Device(object):
             # device is unpaired
             assert self.wpid is not None, 'failed to read wpid: device %d of %s' % (number, receiver)
 
-            self.path = _hid.find_paired_node(receiver.phys, number)
+            self.path = _hid.find_paired_node(receiver.path, number)
             self.handle = _hid.open_path(self.path) if self.path else None
 
             self.descriptor = _DESCRIPTORS.get(self.wpid)

lib/logitech_receiver/receiver.py

@@ -53,7 +53,6 @@ class Receiver(object):
         self.handle = handle
         assert device_info
         self.path = device_info.path
-        self.phys = device_info.phys
         # USB product id, used for some Nano receivers
         self.product_id = device_info.product_id
         product_info = _product_information(self.product_id)