usb: dwc3: gadget: Disable gadget IRQ during pullup disable

Current sequence utilizes dwc3_gadget_disable_irq() alongside
synchronize_irq() to ensure that no further DWC3 events are generated.
However, the dwc3_gadget_disable_irq() API only disables device
specific events.  Endpoint events can still be generated.  Briefly
disable the interrupt line, so that the cleanup code can run to
prevent device and endpoint events. (i.e. __dwc3_gadget_stop() and
dwc3_stop_active_transfers() respectively)

Without doing so, it can lead to both the interrupt handler and the
pullup disable routine both writing to the GEVNTCOUNT register, which
will cause an incorrect count being read from future interrupts.

Fixes: ae7e8610 ("usb: dwc3: Stop active transfers before halting the controller")
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/1621571037-1424-1-git-send-email-wcheng@codeaurora.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/gadget.c

@@ -2261,13 +2261,10 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 	}
 
 	/*
-	 * Synchronize any pending event handling before executing the controller
-	 * halt routine.
+	 * Synchronize and disable any further event handling while controller
+	 * is being enabled/disabled.
 	 */
-	if (!is_on) {
-		dwc3_gadget_disable_irq(dwc);
-		synchronize_irq(dwc->irq_gadget);
-	}
+	disable_irq(dwc->irq_gadget);
 
 	spin_lock_irqsave(&dwc->lock, flags);
 
@@ -2305,6 +2302,8 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 
 	ret = dwc3_gadget_run_stop(dwc, is_on, false);
 	spin_unlock_irqrestore(&dwc->lock, flags);
+	enable_irq(dwc->irq_gadget);
+
 	pm_runtime_put(dwc->dev);
 
 	return ret;