tests: Tolerate USB HID interface

set_configuration() will fail if there's a HID driver attached.
Could probably dropped it entirely, but now it will work even if no kernel
driver has been bound.

The GUD interface isn't necessarily the first one, so accommodate for that.
Drop the reset(), shouldn't be necessary.

Author: notro

tests/gud/__init__.py

@@ -195,41 +195,45 @@ def __init__(self, dev):
         self._formats = None
         self._properties = None
         self._connectors = None
+        self._interface = None
+        self.ep = None
         self.state = None
 
-    def config(self):
-        self.dev.set_configuration()
-        self.interface = None
+    @property
+    def interface(self):
+        if self._interface is not None:
+            return self._interface
+
+        try:
+            self.dev.set_configuration()
+        except usb.core.USBError as e:
+            if e.errno != errno.EBUSY:
+                raise e from None
+        # Pick the first Vendor Class Interface
         for itf in self.dev.get_active_configuration():
             if itf.bInterfaceClass == 0xff:
-                self.interface = itf
-        assert self.interface is not None
+                self._interface = itf
+                break
+        assert self._interface is not None
         self.ep = usb.util.find_descriptor(
-            self.interface,
+            self._interface,
             # match the first OUT endpoint
             custom_match = lambda e: usb.util.endpoint_direction(e.bEndpointAddress) == usb.util.ENDPOINT_OUT)
         assert self.ep is not None
 
-    def _get_ifnum(self, ifnum):
-        if ifnum is None:
-            if self.interface:
-                return self.interface.bInterfaceNumber
-            else:
-                return 0
-        else:
-            return ifnum
+        return self._interface
 
     def reset(self):
         self.dev.reset()
 
-    def is_kernel_driver_active(self, ifnum=None):
-        return self.dev.is_kernel_driver_active(self._get_ifnum(ifnum))
+    def is_kernel_driver_active(self):
+        return self.dev.is_kernel_driver_active(self.interface.bInterfaceNumber)
 
-    def detach_kernel_driver(self, ifnum=None):
-        self.dev.detach_kernel_driver(self._get_ifnum(ifnum))
+    def detach_kernel_driver(self):
+        self.dev.detach_kernel_driver(self.interface.bInterfaceNumber)
 
-    def attach_kernel_driver(self, ifnum=None):
-        self.dev.attach_kernel_driver(self._get_ifnum(ifnum))
+    def attach_kernel_driver(self):
+        self.dev.attach_kernel_driver(self.interface.bInterfaceNumber)
 
     @property
     def descriptor(self):
@@ -506,10 +510,8 @@ def find_first_setup():
     dev = find()
     if not dev:
         return None
-    if dev.is_kernel_driver_active(0):
-        dev.detach_kernel_driver(0)
-    dev.reset()
-    dev.config()
+    if dev.is_kernel_driver_active():
+        dev.detach_kernel_driver()
     for connector in dev.connectors:
         connector.update()
     return dev