USB: EHCI: add need_io_watchdog flag to ehci_hcd

Basically the io watchdog is only useful for those quirk HCDs. For most
good ones, it only brings unnecessary wakeups. At least, I know the
Intel EHCI HCDs should turn off the flag.

Signed-off-by: Alek Du <[e-mail]>
Cc: David Brownell <[e-mail]>
Cc: Alan Stern <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ehci-hcd.c

···
 
 		switch (action) {
 		case TIMER_IO_WATCHDOG:
+			if (!ehci->need_io_watchdog)
+				return;
 			t = EHCI_IO_JIFFIES;
 			break;
 		case TIMER_ASYNC_OFF:
···
 
 	spin_lock_init(&ehci->lock);
 
+	/*
+	 * keep io watchdog by default, those good HCDs could turn off it later
+	 */
+	ehci->need_io_watchdog = 1;
 	init_timer(&ehci->watchdog);
 	ehci->watchdog.function = ehci_watchdog;
 	ehci->watchdog.data = (unsigned long) ehci;

drivers/usb/host/ehci-pci.c

···
 		return retval;
 
 	switch (pdev->vendor) {
+	case PCI_VENDOR_ID_INTEL:
+		ehci->need_io_watchdog = 0;
+		break;
 	case PCI_VENDOR_ID_TDI:
 		if (pdev->device == PCI_DEVICE_ID_TDI_EHCI) {
 			hcd->has_tt = 1;

drivers/usb/host/ehci.h

···
 	unsigned		big_endian_mmio:1;
 	unsigned		big_endian_desc:1;
 	unsigned		has_amcc_usb23:1;
+	unsigned		need_io_watchdog:1;
 
 	/* required for usb32 quirk */
 	#define OHCI_CTRL_HCFS          (3 << 6)