clean up

src/class/midi/midi_device.c

@@ -375,6 +375,9 @@ uint16_t midid_open(uint8_t rhport, tusb_desc_interface_t const * desc_itf, uint
   return drv_len;
 }
 
+// Invoked when a control transfer occurred on an interface of this class
+// Driver response accordingly to the request and the transfer stage (setup/data/ack)
+// return false to stall control endpoint (e.g unsupported request)
 bool midid_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request)
 {
   (void) rhport;