usb: dwc3: gadget: clear DWC3_EP_TRANSFER_STARTED on cmd complete

[ Upstream commit acbfa6c2 ]

We must wait until End Transfer completes in order to clear
DWC3_EP_TRANSFER_STARTED, otherwise we may confuse the driver.

This patch is in preparation to fix a rare race condition that happens
upon Disconnect Interrupt.
Tested-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/usb/dwc3/gadget.c

@@ -375,19 +375,9 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned cmd,
 
 	trace_dwc3_gadget_ep_cmd(dep, cmd, params, cmd_status);
 
-	if (ret == 0) {
-		switch (DWC3_DEPCMD_CMD(cmd)) {
-		case DWC3_DEPCMD_STARTTRANSFER:
-			dep->flags |= DWC3_EP_TRANSFER_STARTED;
-			dwc3_gadget_ep_get_transfer_index(dep);
-			break;
-		case DWC3_DEPCMD_ENDTRANSFER:
-			dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
-			break;
-		default:
-			/* nothing */
-			break;
-		}
+	if (ret == 0 && DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
+		dep->flags |= DWC3_EP_TRANSFER_STARTED;
+		dwc3_gadget_ep_get_transfer_index(dep);
 	}
 
 	if (unlikely(susphy)) {
@@ -2417,7 +2407,8 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 		cmd = DEPEVT_PARAMETER_CMD(event->parameters);
 
 		if (cmd == DWC3_DEPCMD_ENDTRANSFER) {
-			dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
+			dep->flags &= ~(DWC3_EP_END_TRANSFER_PENDING |
+					DWC3_EP_TRANSFER_STARTED);
 			dwc3_gadget_ep_cleanup_cancelled_requests(dep);
 		}
 		break;