USB: Handle auto-transition from hot to warm reset.

commit 1c7439c6 upstream.

USB 3.0 hubs and roothubs will automatically transition a failed hot
reset to a warm (BH) reset.  In that case, the warm reset change bit
will be set, and the link state change bit may also be set.  Change
hub_port_finish_reset to unconditionally clear those change bits for USB
3.0 hubs.  If these bits are not cleared, we may lose port change events
from the roothub.

This commit should be backported to kernels as old as 3.2, that contain
the commit 75d7cf72 "usbcore: refine
warm reset logic".
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/core/hub.c

@@ -2186,16 +2186,16 @@ static void hub_port_finish_reset(struct usb_hub *hub, int port1,
 		clear_port_feature(hub->hdev,
 				port1, USB_PORT_FEAT_C_RESET);
 		/* FIXME need disconnect() for NOTATTACHED device */
-		if (warm) {
+		if (hub_is_superspeed(hub->hdev)) {
 			clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_BH_PORT_RESET);
 			clear_port_feature(hub->hdev, port1,
 					USB_PORT_FEAT_C_PORT_LINK_STATE);
-		} else {
+		}
+		if (!warm)
 			usb_set_device_state(udev, *status
 					? USB_STATE_NOTATTACHED
 					: USB_STATE_DEFAULT);
-		}
 		break;
 	}
 }