added optional dcd_control_status_complete()

src/device/dcd.h

@@ -119,6 +119,10 @@ void dcd_edpt_stall       (uint8_t rhport, uint8_t ep_addr);
 // clear stall, data toggle is also reset to DATA0
 void dcd_edpt_clear_stall (uint8_t rhport, uint8_t ep_addr);
 
+// Invoked when a control transfer's status stage is complete.
+// May help DCD to prepare for next control transfer, this API is optional.
+void dcd_control_status_complete(uint8_t rhport) TU_ATTR_WEAK;
+
 //--------------------------------------------------------------------+
 // Event API
 //--------------------------------------------------------------------+

src/device/usbd_control.c

@@ -129,6 +129,7 @@ bool usbd_control_xfer_cb (uint8_t rhport, uint8_t ep_addr, xfer_result_t result
   if ( tu_edpt_dir(ep_addr) != _ctrl_xfer.request.bmRequestType_bit.direction )
   {
     TU_ASSERT(0 == xferred_bytes);
+    if (dcd_control_status_complete) dcd_control_status_complete(rhport);
     return true;
   }