Revert "USBDevice: interrupts are now enabled on init"

This reverts commit a8d208a.

Fixes #423 on Linux/Mac (and Windows when Arduino standard drivers are uninstalled)

Fix for normal behaviour on Windows is ongoing

Author: facchinm

Diff for: cores/arduino/USB/CDC.cpp

@@ -27,6 +27,8 @@
 
 #ifdef CDC_ENABLED
 
+extern USBDevice_SAMD21G18x usbd;
+
 #define CDC_SERIAL_BUFFER_SIZE	256
 
 /* For information purpose only since RTS is not always handled by the terminal application */
@@ -184,6 +186,11 @@ Serial_::Serial_(USBDeviceClass &_usb) : PluggableUSBModule(3, 2, epType), usb(_
   PluggableUSB().plug(this);
 }
 
+void Serial_::enableInterrupt() {
+	usbd.epBank1EnableTransferComplete(CDC_ENDPOINT_ACM);
+	usbd.epBank0EnableTransferComplete(CDC_ENDPOINT_OUT);
+}
+
 void Serial_::begin(uint32_t /* baud_count */)
 {
 	// uart config is ignored in USB-CDC

Diff for: cores/arduino/USB/CDC.h

@@ -144,6 +144,7 @@ class Serial_ : public Stream, public PluggableUSBModule {
     bool setup(USBSetup& setup);
     uint8_t getShortName(char* name);
     void handleEndpoint(int ep);
+    void enableInterrupt();
 
 friend USBDeviceClass;
 

Diff for: cores/arduino/USB/USBCore.cpp

@@ -405,7 +405,6 @@ void USBDeviceClass::initEP(uint32_t ep, uint32_t config)
 		usbd.epBank1SetSize(ep, 64);
 		usbd.epBank1SetAddress(ep, &udd_ep_in_cache_buffer[ep]);
 		usbd.epBank1SetType(ep, 4); // INTERRUPT IN
-		usbd.epBank1EnableTransferComplete(ep);
 	}
 	else if (config == (USB_ENDPOINT_TYPE_BULK | USB_ENDPOINT_OUT(0)))
 	{
@@ -419,9 +418,6 @@ void USBDeviceClass::initEP(uint32_t ep, uint32_t config)
 		usbd.epBank1SetSize(ep, 64);
 		usbd.epBank1SetAddress(ep, &udd_ep_in_cache_buffer[ep]);
 		usbd.epBank1SetType(ep, 3); // BULK IN
-
-		// XXX: this somehow interfere with CDC rx - WHY???
-		// usbd.epBank1EnableTransferComplete(ep);
 	}
 	else if (config == USB_ENDPOINT_TYPE_CONTROL)
 	{
@@ -437,9 +433,6 @@ void USBDeviceClass::initEP(uint32_t ep, uint32_t config)
 
 		// Release OUT EP
 		usbd.epReleaseOutBank0(ep, 64);
-
-		// Enable Setup-Received interrupt
-		usbd.epBank0EnableSetupReceived(ep);
 	}
 }
 
@@ -796,6 +789,10 @@ bool USBDeviceClass::handleStandardSetup(USBSetup &setup)
 			initEndpoints();
 			_usbConfiguration = setup.wValueL;
 
+			#ifdef CDC_ENABLED
+			SerialUSB.enableInterrupt();
+			#endif
+
 			sendZlp(0);
 			return true;
 		} else {
@@ -831,6 +828,9 @@ void USBDeviceClass::ISRHandler()
 		// Configure EP 0
 		initEP(0, USB_ENDPOINT_TYPE_CONTROL);
 
+		// Enable Setup-Received interrupt
+		usbd.epBank0EnableSetupReceived(0);
+
 		_usbConfiguration = 0;
 	}