usb: dwc3: ep0: Don't prepare beyond Setup stage

Since we can't guarantee that the host won't send new Setup packet
before going through the device-initiated disconnect, don't prepare
beyond the Setup stage and keep the device in EP0_SETUP_PHASE. This
ensures that the device-initated disconnect sequence can go through
gracefully. Note that the controller won't service the End Transfer
command if it can't DMA out the Setup packet.
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/6bacec56ecabb2c6e49a09cedfcac281fdc97de0.1650593829.git.Thinh.Nguyen@synopsys.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/ep0.c

@@ -813,7 +813,7 @@ static void dwc3_ep0_inspect_setup(struct dwc3 *dwc,
 	int ret = -EINVAL;
 	u32 len;
 
-	if (!dwc->gadget_driver)
+	if (!dwc->gadget_driver || !dwc->connected)
 		goto out;
 
 	trace_dwc3_ctrl_req(ctrl);

drivers/usb/dwc3/gadget.c

@@ -2514,6 +2514,23 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->connected = false;
 
+	/*
+	 * Per databook, when we want to stop the gadget, if a control transfer
+	 * is still in process, complete it and get the core into setup phase.
+	 */
+	if (dwc->ep0state != EP0_SETUP_PHASE) {
+		int ret;
+
+		reinit_completion(&dwc->ep0_in_setup);
+
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
+				msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
+		spin_lock_irqsave(&dwc->lock, flags);
+		if (ret == 0)
+			dev_warn(dwc->dev, "timed out waiting for SETUP phase\n");
+	}
+
 	/*
 	 * In the Synopsys DesignWare Cores USB3 Databook Rev. 3.30a
 	 * Section 4.1.8 Table 4-7, it states that for a device-initiated
@@ -2546,18 +2563,6 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 		return 0;
 
 	dwc->softconnect = is_on;
-	/*
-	 * Per databook, when we want to stop the gadget, if a control transfer
-	 * is still in process, complete it and get the core into setup phase.
-	 */
-	if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {
-		reinit_completion(&dwc->ep0_in_setup);
-
-		ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
-				msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
-		if (ret == 0)
-			dev_warn(dwc->dev, "timed out waiting for SETUP phase\n");
-	}
 
 	/*
 	 * Avoid issuing a runtime resume if the device is already in the