usb: dwc3: clear 'res_trans_idx' as soon as it becomes invalid

Transfer resource index is cleared in hardware when XFERCOMPLETE
event is generated, so clear the driver's res_trans_idx variable
immediately after that event is received. The upcoming hibernation
patches depend on this change.
Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/ep0.c

@@ -617,6 +617,7 @@ static void dwc3_ep0_xfer_complete(struct dwc3 *dwc,
 	struct dwc3_ep		*dep = dwc->eps[event->endpoint_number];
 
 	dep->flags &= ~DWC3_EP_BUSY;
+	dep->res_trans_idx = 0;
 	dwc->setup_packet_pending = false;
 
 	switch (dwc->ep0state) {

drivers/usb/dwc3/gadget.c

@@ -1628,10 +1628,8 @@ static void dwc3_endpoint_transfer_complete(struct dwc3 *dwc,
 		status = -ECONNRESET;
 
 	clean_busy = dwc3_cleanup_done_reqs(dwc, dep, event, status);
-	if (clean_busy) {
+	if (clean_busy)
 		dep->flags &= ~DWC3_EP_BUSY;
-		dep->res_trans_idx = 0;
-	}
 
 	/*
 	 * WORKAROUND: This is the 2nd half of U1/U2 -> U0 workaround.
@@ -1736,6 +1734,8 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 
 	switch (event->endpoint_event) {
 	case DWC3_DEPEVT_XFERCOMPLETE:
+		dep->res_trans_idx = 0;
+
 		if (usb_endpoint_xfer_isoc(dep->desc)) {
 			dev_dbg(dwc->dev, "%s is an Isochronous endpoint\n",
 					dep->name);