usb: dwc3: gadget: Do not clear ep delayed stop flag during ep disable

DWC3_EP_DELAYED_STOP is utilized to defer issuing the end transfer command
until the subsequent SETUP stage, in order to avoid end transfer timeouts.
During cable disconnect scenarios, __dwc3_gadget_ep_disable() is
responsible for ensuring endpoints have no active transfers pending.  Since
dwc3_remove_request() can now exit early if the EP delayed stop is set,
avoid clearing all DEP flags, otherwise the transition back into the SETUP
stage won't issue an endxfer command.

Fixes: 2b2da657 ("usb: dwc3: Avoid unmapping USB requests if endxfer is not complete")
Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20220919231213.21364-1-quic_wcheng@quicinc.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/gadget.c

@@ -1011,6 +1011,7 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
 {
 	struct dwc3		*dwc = dep->dwc;
 	u32			reg;
+	u32			mask;
 
 	trace_dwc3_gadget_ep_disable(dep);
 
@@ -1032,7 +1033,15 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
 
 	dep->stream_capable = false;
 	dep->type = 0;
-	dep->flags &= DWC3_EP_TXFIFO_RESIZED;
+	mask = DWC3_EP_TXFIFO_RESIZED;
+	/*
+	 * dwc3_remove_requests() can exit early if DWC3 EP delayed stop is
+	 * set.  Do not clear DEP flags, so that the end transfer command will
+	 * be reattempted during the next SETUP stage.
+	 */
+	if (dep->flags & DWC3_EP_DELAY_STOP)
+		mask |= (DWC3_EP_DELAY_STOP | DWC3_EP_TRANSFER_STARTED);
+	dep->flags &= mask;
 
 	return 0;
 }