redragon-lights.py: fix USB reset errors

redragon-lights.py

@@ -8,8 +8,8 @@ import gi.repository.GLib
 import pprint
 import sys
 import time
+import traceback
 import usb.core
-#import traceback
 
 # Redragon K621 Horus
 vendor=0x258a
@@ -168,17 +168,60 @@ def send_packets(kbd, switch):
     try:
         ret = kbd.ctrl_transfer(0x21, 0x09, 0x0306, 1, msg)
         assert ret == len(msg)
-        # Prevent [Errno 32] Pipe error
-        #time.sleep(0.25)
+        # Prevent [Errno 32] Pipe error when running multiple commands, if we add any more ctrl_transfer()s after this one
+        time.sleep(0.25)
     except usb.core.USBError as e:
         print(e)
         if e.errno == 16:
             print("This issue needs more investigation... it may simply be previous invalid commands")
+            # The issue seems to be that the device configuration loses the report descriptors for interface 1 (the second interface)
             # May need to reconfigure the device, or detach/reattach kernel driver, either for interface 0 or 0 _and_ 1
-            # if detaching/reattaching, swallow errors with try/except
+            reset_driver(kbd)
         elif e.errno == 2:
             print("Try unplugging and replugging the keyboard...")
-        sys.exit()
+
+
+def reset_driver(kbd):
+    global debug
+    interfaces = list()
+    for cfg in kbd:
+        for intf in cfg:
+            interfaces.append(intf.bInterfaceNumber)
+
+    # Remove the driver
+    for intfNum in interfaces:
+        if kbd.is_kernel_driver_active(intfNum) is False:
+            print("kernel driver already detached")
+        else:
+            print("detaching kernel driver for interface {}".format(intfNum), flush=True)
+            try:
+                kbd.detach_kernel_driver(intfNum)
+            except usb.core.USBError as e:
+                print('Could not detach kernel driver: %s' % str(e), flush=True)
+                print(traceback.format_exc(), flush=True)
+
+    # Send a command (I think this is a short command to get the current keyboard state)
+    # This seems to reset things
+    msg = [ 0x05, 0x83, 0xc6, 0x00, 0x00, 0x00 ]
+    try:
+        print("trying to get kbd state")
+        ret = kbd.ctrl_transfer(0x21, 0x09, 0x0305, 1, msg)
+        #print(len(msg))
+        #print(ret)
+        assert ret == len(msg)
+    except:
+        pass
+
+    # Re-add driver
+    for intfNum in interfaces:
+        if kbd.is_kernel_driver_active(intfNum):
+            print("kernel driver already attached")
+        else:
+            print("reattaching kernel driver for interface {}".format(intfNum), flush=True)
+            try:
+                kbd.attach_kernel_driver(intfNum)
+            except usb.core.USBError as e:
+                print('Could not reattach kernel driver: %s' % str(e), flush=True)
 
 
 if __name__ == '__main__':