usb: at91_udc: correct hanging while disconnecting usb cable

Correct hanging while disconnecting the USB device cable. Prevent a race between vbus and UDP interrupts. This bug was tracked on at91sam9260ek boards.

A usb resume interrupt was firing after the vbus interrupt : the IP was then already stoped and not able to deal with it (no more clock). A simple interrupt disabling is ok as the "end of bus reset" irq is non maskable and ok to resume the USB device IP.

@@ -908,6 +908,7 @@ static void pullup(struct at91_udc *udc,
 

	if (is_on) {
		clk_on(udc);
+		at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXRSM);
		at91_udp_write(udc, AT91_UDP_TXVC, 0);
		if (cpu_is_at91rm9200())
			at91_set_gpio_value(udc->board.pullup_pin, 1);
@@ -925,6 +926,7 @@ static void pullup(struct at91_udc *udc,
		}
	} else {
		stop_activity(udc);
+		at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXRSM);
		at91_udp_write(udc, AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
		if (cpu_is_at91rm9200())
			at91_set_gpio_value(udc->board.pullup_pin, 0);

Good, thanks for finding this. The bug was reported recently, and obviously can't be reproduced except on boards which *have* a VBUS interrupt!

I've signed off on this and suggested Greg merge it before the 2.6.24-final freeze.

- Dave