xhci: don't try to reset the host if it is unaccessible

There is no point in trying to reset the host controller by writing
to its registers if host is removed and registers just return 0xffffffff

bail out and return -ENODEV instead

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci.c

@@ -167,6 +167,12 @@ int xhci_reset(struct xhci_hcd *xhci)
 	int ret, i;
 
 	state = readl(&xhci->op_regs->status);
+
+	if (state == ~(u32)0) {
+		xhci_warn(xhci, "Host not accessible, reset failed.\n");
+		return -ENODEV;
+	}
+
 	if ((state & STS_HALT) == 0) {
 		xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
 		return 0;
@@ -690,7 +696,6 @@ void xhci_stop(struct usb_hcd *hcd)
 		xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
 		xhci_halt(xhci);
 		xhci_reset(xhci);
-
 		spin_unlock_irq(&xhci->lock);
 	}