usb: core: Fix hub port connection events lost

This will clear the USB_PORT_FEAT_C_CONNECTION bit in case of a hub port reset
only if a device is was attached to the hub port before resetting the hub port.

Using a Lenovo T480s attached to the ultra dock it was not possible to detect
some usb-c devices at the dock usb-c ports because the hub_port_reset code
will clear the USB_PORT_FEAT_C_CONNECTION bit after the actual hub port reset.
Using this device combo the USB_PORT_FEAT_C_CONNECTION bit was set between the
actual hub port reset and the clear of the USB_PORT_FEAT_C_CONNECTION bit.
This ends up with clearing the USB_PORT_FEAT_C_CONNECTION bit after the
new device was attached such that it was not detected.

This patch will not clear the USB_PORT_FEAT_C_CONNECTION bit if there is
currently no device attached to the port before the hub port reset.
This will avoid clearing the connection bit for new attached devices.
Signed-off-by: Dennis Wassenberg <dennis.wassenberg@secunet.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/hub.c

@@ -2850,6 +2850,8 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 					USB_PORT_FEAT_C_BH_PORT_RESET);
 			usb_clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_PORT_LINK_STATE);
+
+			if (udev)
 				usb_clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_CONNECTION);