static int set_alternate(struct camera_data *cam, unsigned int alt)
{
	int ret = 0;

	if(alt == cam->cur_alt)
		return 0;

	if (cam->cur_alt != USBIF_CMDONLY) {
		DBG("Changing from alt %d to %d\n", cam->cur_alt, USBIF_CMDONLY);
		ret = usb_set_interface(cam->dev, cam->iface, USBIF_CMDONLY);
		if (ret != 0)
			return ret;
	}
	if (alt != USBIF_CMDONLY) {
		DBG("Changing from alt %d to %d\n", USBIF_CMDONLY, alt);
		ret = usb_set_interface(cam->dev, cam->iface, alt);
		if (ret != 0)
			return ret;
	}

	cam->old_alt = cam->cur_alt;
	cam->cur_alt = alt;

	return ret;
}
Unknown