usb: dwc3: Abort suspend on soft disconnect failure

When dwc3_gadget_soft_disconnect() fails, dwc3_suspend_common() keeps
going with the suspend, resulting in a period where the power domain is
off, but the gadget driver remains connected.  Within this time frame,
invoking vbus_event_work() will cause an error as it attempts to access
DWC3 registers for endpoint disabling after the power domain has been
completely shut down.

Abort the suspend sequence when dwc3_gadget_suspend() cannot halt the
controller and proceeds with a soft connect.

Fixes: 9f8a67b ("usb: dwc3: gadget: fix gadget suspend/resume")
Cc: stable <stable@kernel.org>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://lore.kernel.org/r/20250528100315.2162699-1-khtsai@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Kuen-Han Tsai

drivers/usb/dwc3/core.c

@@ -2422,6 +2422,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 {
 	u32 reg;
 	int i;
+	int ret;
 
 	if (!pm_runtime_suspended(dwc->dev) && !PMSG_IS_AUTO(msg)) {
 		dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
@@ -2440,7 +2441,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 	case DWC3_GCTL_PRTCAP_DEVICE:
 		if (pm_runtime_suspended(dwc->dev))
 			break;
-		dwc3_gadget_suspend(dwc);
+		ret = dwc3_gadget_suspend(dwc);
+		if (ret)
+			return ret;
 		synchronize_irq(dwc->irq_gadget);
 		dwc3_core_exit(dwc);
 		break;
@@ -2475,7 +2478,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 			break;
 
 		if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
-			dwc3_gadget_suspend(dwc);
+			ret = dwc3_gadget_suspend(dwc);
+			if (ret)
+				return ret;
 			synchronize_irq(dwc->irq_gadget);
 		}
 

drivers/usb/dwc3/gadget.c

@@ -4821,26 +4821,22 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
 	int ret;
 
 	ret = dwc3_gadget_soft_disconnect(dwc);
-	if (ret)
-		goto err;
-
-	spin_lock_irqsave(&dwc->lock, flags);
-	if (dwc->gadget_driver)
-		dwc3_disconnect_gadget(dwc);
-	spin_unlock_irqrestore(&dwc->lock, flags);
-
-	return 0;
-
-err:
 	/*
 	 * Attempt to reset the controller's state. Likely no
 	 * communication can be established until the host
 	 * performs a port reset.
 	 */
-	if (dwc->softconnect)
+	if (ret && dwc->softconnect) {
 		dwc3_gadget_soft_connect(dwc);
+		return -EAGAIN;
+	}
 
-	return ret;
+	spin_lock_irqsave(&dwc->lock, flags);
+	if (dwc->gadget_driver)
+		dwc3_disconnect_gadget(dwc);
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	return 0;
 }
 
 int dwc3_gadget_resume(struct dwc3 *dwc)