static int hub_port_reset(struct usb_hub *hub, int port1,
			struct usb_device *udev, unsigned int delay, bool warm)
{
	int i, status;
	u16 portchange, portstatus;
	struct usb_port *port_dev = hub->ports[port1 - 1];

	if (!hub_is_superspeed(hub->hdev)) {
		if (warm) {
			dev_err(hub->intfdev, "only USB3 hub support "
						"warm reset\n");
			return -EINVAL;
		}
		/* Block EHCI CF initialization during the port reset.
		 * Some companion controllers don't like it when they mix.
		 */
		down_read(&ehci_cf_port_reset_rwsem);
	} else if (!warm) {
		/*
		 * If the caller hasn't explicitly requested a warm reset,
		 * double check and see if one is needed.
		 */
		if (hub_port_status(hub, port1, &portstatus, &portchange) == 0)
			if (hub_port_warm_reset_required(hub, port1,
							portstatus))
				warm = true;
	}
	clear_bit(port1, hub->warm_reset_bits);

	/* Reset the port */
	for (i = 0; i < PORT_RESET_TRIES; i++) {
		status = set_port_feature(hub->hdev, port1, (warm ?
					USB_PORT_FEAT_BH_PORT_RESET :
					USB_PORT_FEAT_RESET));
		if (status == -ENODEV) {
			;	/* The hub is gone */
		} else if (status) {
			dev_err(&port_dev->dev,
					"cannot %sreset (err = %d)\n",
					warm ? "warm " : "", status);
		} else {
			status = hub_port_wait_reset(hub, port1, udev, delay,
								warm);
			if (status && status != -ENOTCONN && status != -ENODEV)
				dev_dbg(hub->intfdev,
						"port_wait_reset: err = %d\n",
						status);
		}

		/* Check for disconnect or reset */
		if (status == 0 || status == -ENOTCONN || status == -ENODEV) {
			usb_clear_port_feature(hub->hdev, port1,
					USB_PORT_FEAT_C_RESET);

			if (!hub_is_superspeed(hub->hdev))
				goto done;

			usb_clear_port_feature(hub->hdev, port1,
					USB_PORT_FEAT_C_BH_PORT_RESET);
			usb_clear_port_feature(hub->hdev, port1,
					USB_PORT_FEAT_C_PORT_LINK_STATE);
			usb_clear_port_feature(hub->hdev, port1,
					USB_PORT_FEAT_C_CONNECTION);

			/*
			 * If a USB 3.0 device migrates from reset to an error
			 * state, re-issue the warm reset.
			 */
			if (hub_port_status(hub, port1,
					&portstatus, &portchange) < 0)
				goto done;

			if (!hub_port_warm_reset_required(hub, port1,
					portstatus))
				goto done;

			/*
			 * If the port is in SS.Inactive or Compliance Mode, the
			 * hot or warm reset failed.  Try another warm reset.
			 */
			if (!warm) {
				dev_dbg(&port_dev->dev,
						"hot reset failed, warm reset\n");
				warm = true;
			}
		}

		dev_dbg(&port_dev->dev,
				"not enabled, trying %sreset again...\n",
				warm ? "warm " : "");
		delay = HUB_LONG_RESET_TIME;
	}

	dev_err(&port_dev->dev, "Cannot enable. Maybe the USB cable is bad?\n");

done:
	if (status == 0) {
		/* TRSTRCY = 10 ms; plus some extra */
		msleep(10 + 40);
		if (udev) {
			struct usb_hcd *hcd = bus_to_hcd(udev->bus);

			update_devnum(udev, 0);
			/* The xHC may think the device is already reset,
			 * so ignore the status.
			 */
			if (hcd->driver->reset_device)
				hcd->driver->reset_device(hcd, udev);

			usb_set_device_state(udev, USB_STATE_DEFAULT);
		}
	} else {
		if (udev)
			usb_set_device_state(udev, USB_STATE_NOTATTACHED);
	}

	if (!hub_is_superspeed(hub->hdev))
		up_read(&ehci_cf_port_reset_rwsem);

	return status;
}

Unknown