usb: dwc2: gadget: prevent new request submission during suspend

If usb controller is in partial power down, any write to registers may
cause unpredictable behavior.
Thus, prevent any new request submission once controller is in partial
power down.
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc2/gadget.c

@@ -790,6 +790,13 @@ static int s3c_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
 		ep->name, req, req->length, req->buf, req->no_interrupt,
 		req->zero, req->short_not_ok);
 
+	/* Prevent new request submission when controller is suspended */
+	if (hs->lx_state == DWC2_L2) {
+		dev_dbg(hs->dev, "%s: don't submit request while suspended\n",
+				__func__);
+		return -EAGAIN;
+	}
+
 	/* initialise status of the request */
 	INIT_LIST_HEAD(&hs_req->queue);
 	req->actual = 0;