usb: xhci: rework root port wake bits if controller isn't allowed to wakeup

When system is being suspended, if host device is not allowed to do wakeup,
xhci_suspend() needs to clear all root port wake on bits. Otherwise, some
platforms may generate spurious wakeup, even if PCI PME# is disabled.

The initial commit ff8cbf250b44 ("xhci: clear root port wake on bits"),
which also got into stable, turned out to not work correctly and had to
be reverted, and is now rewritten.

Cc: stable <stable@vger.kernel.org> # v3.2+
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
[Mathias Nyman: reword commit message]
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 3d78b0c..646300c 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -204,7 +204,15 @@
 	struct usb_hcd	*hcd = dev_get_drvdata(dev);
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 
-	return xhci_suspend(xhci);
+	/*
+	 * xhci_suspend() needs `do_wakeup` to know whether host is allowed
+	 * to do wakeup during suspend. Since xhci_plat_suspend is currently
+	 * only designed for system suspend, device_may_wakeup() is enough
+	 * to dertermine whether host is allowed to do wakeup. Need to
+	 * reconsider this when xhci_plat_suspend enlarges its scope, e.g.,
+	 * also applies to runtime suspend.
+	 */
+	return xhci_suspend(xhci, device_may_wakeup(dev));
 }
 
 static int xhci_plat_resume(struct device *dev)