USB: gpio_vbus: provide an appropriate debounce interval

In commit c2344f1 (USB: gpio_vbus:
add delayed vbus_session calls, 2009-01-24), usb_gadget_vbus_connect()
and ...disconnect() were extracted from the interrupt handler, so to
allow vbus_session handlers to deal with msleep() calls.

This patch takes the approach one step further.

USB2.0 specification (7.1.7.3 Connect and Disconnect Signaling) says
that the USB system software (shall) provide a debounce interval with
a minimum duration of 100 ms, which ensures that the electrical and
mechanical connection is stable before software attempts to reset
the attached device.

Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/otg/gpio_vbus.c

@@ -37,7 +37,7 @@ struct gpio_vbus_data {
 	struct regulator       *vbus_draw;
 	int			vbus_draw_enabled;
 	unsigned		mA;
-	struct work_struct	work;
+	struct delayed_work	work;
 };
 
 
@@ -94,7 +94,7 @@ static int is_vbus_powered(struct gpio_vbus_mach_info *pdata)
 static void gpio_vbus_work(struct work_struct *work)
 {
 	struct gpio_vbus_data *gpio_vbus =
-		container_of(work, struct gpio_vbus_data, work);
+		container_of(work, struct gpio_vbus_data, work.work);
 	struct gpio_vbus_mach_info *pdata = gpio_vbus->dev->platform_data;
 	int gpio, status;
 
@@ -152,7 +152,7 @@ static irqreturn_t gpio_vbus_irq(int irq, void *data)
 		otg->gadget ? otg->gadget->name : "none");
 
 	if (otg->gadget)
-		schedule_work(&gpio_vbus->work);
+		schedule_delayed_work(&gpio_vbus->work, msecs_to_jiffies(100));
 
 	return IRQ_HANDLED;
 }
@@ -300,7 +300,7 @@ static int __init gpio_vbus_probe(struct platform_device *pdev)
 
 	ATOMIC_INIT_NOTIFIER_HEAD(&gpio_vbus->phy.notifier);
 
-	INIT_WORK(&gpio_vbus->work, gpio_vbus_work);
+	INIT_DELAYED_WORK(&gpio_vbus->work, gpio_vbus_work);
 
 	gpio_vbus->vbus_draw = regulator_get(&pdev->dev, "vbus_draw");
 	if (IS_ERR(gpio_vbus->vbus_draw)) {