fotg210-udc: Complete OUT requests on short packets

A short packet indicates the end of a transfer and marks the request as
complete.

Fixes: b84a8dee ("usb: gadget: add Faraday fotg210_udc driver")
Signed-off-by: Fabian Vogt <fabian@ritter-vogt.de>
Link: https://lore.kernel.org/r/20210324141115.9384-8-fabian@ritter-vogt.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/fotg210-udc.c

@@ -849,12 +849,16 @@ static void fotg210_out_fifo_handler(struct fotg210_ep *ep)
 {
 	struct fotg210_request *req = list_entry(ep->queue.next,
 						 struct fotg210_request, queue);
+	int disgr1 = ioread32(ep->fotg210->reg + FOTG210_DISGR1);
 
 	fotg210_start_dma(ep, req);
 
-	/* finish out transfer */
+	/* Complete the request when it's full or a short packet arrived.
+	 * Like other drivers, short_not_ok isn't handled.
+	 */
+
 	if (req->req.length == req->req.actual ||
-	    req->req.actual < ep->ep.maxpacket)
+	    (disgr1 & DISGR1_SPK_INT(ep->epnum - 1)))
 		fotg210_done(ep, req, 0);
 }