USB: switch ehci-hcd to new polling scheme

Switch ehci-hcd to use the new polling scheme, which reports root
hub status changes via the interrupt handler, in an asynchronous
fashion. Doing so disables polling for status changes (whose handler is
rh_timer_func).

Tested on a Geode GX machine, which is now capable of running at =~ 5
timer interrupts per second (in the -rt tree), resulting in significant
power savings.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ehci-hcd.c

@@ -501,6 +501,9 @@ static int ehci_run (struct usb_hcd *hcd)
 	u32			temp;
 	u32			hcc_params;
 
+	hcd->uses_new_polling = 1;
+	hcd->poll_rh = 0;
+
 	/* EHCI spec section 4.1 */
 	if ((retval = ehci_reset(ehci)) != 0) {
 		ehci_mem_cleanup(ehci);
@@ -574,7 +577,7 @@ static int ehci_run (struct usb_hcd *hcd)
 static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
-	u32			status;
+	u32			status, pcd_status = 0;
 	int			bh;
 
 	spin_lock (&ehci->lock);
@@ -624,6 +627,7 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 	/* remote wakeup [4.3.1] */
 	if (status & STS_PCD) {
 		unsigned	i = HCS_N_PORTS (ehci->hcs_params);
+		pcd_status = status;
 
 		/* resume root hub? */
 		if (!(ehci_readl(ehci, &ehci->regs->command) & CMD_RUN))
@@ -670,6 +674,8 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 	if (bh)
 		ehci_work (ehci);
 	spin_unlock (&ehci->lock);
+	if (pcd_status & STS_PCD)
+		usb_hcd_poll_rh_status(hcd);
 	return IRQ_HANDLED;
 }