V4L2_INT_WRAPPER_1(g_fmt_cap, struct v4l2_format, *);

static inline int vidioc_int_#
                        arg_type asterisk arg)	
    {								
        return v4l2_int_ioctl_1(d, vidioc_int_##name##_num,		// vidioc_int_g_fmt_cap_num
                    (void *)(unsigned long)arg);
            /*
			 * 二分查找法执行对应的func，然后执行
			 * 使用vidioc_int_g_fmt_cap_num找到slave中对应的函数
			 */
            return ((v4l2_int_ioctl_func_1 *)
                find_ioctl(d->u.slave, cmd,
                       (v4l2_int_ioctl_func *)no_such_ioctl_1))(d, arg);	// ioctl_g_fmt_cap(d, arg);
    }

static long (struct file *file,
			    unsigned int ioctlnr, void *arg)
{
    case VIDIOC_G_STD: {
        v4l2_std_id *e = arg;
        retval = mxc_v4l2_g_std(cam, e);
            tv_fmt.type = V4L2_BUF_TYPE_PRIVATE;
            vidioc_int_g_fmt_cap(cam->sensor, &tv_fmt);	// 调用slave的回调函数
            *e = tv_fmt.fmt.pix.pixelformat;
        break;
    }
}

static struct v4l2_int_ioctl_desc adw10023_ioctl_desc[] = {
    {vidioc_int_g_fmt_cap_num, (v4l2_int_ioctl_func*)ioctl_g_fmt_cap},	// 定义对应关系
    ...
};

static struct v4l2_int_slave adw10023_slave = {
    .ioctls = adw10023_ioctl_desc,
    .num_ioctls = ARRAY_SIZE(adw10023_ioctl_desc),
};

static struct v4l2_int_device adw10023_int_device = {
    .module = THIS_MODULE,
    .name = "adw10023",
    .type = v4l2_int_type_slave,
    .u = {
        .slave = &adw10023_slave,
    },
};

static int adw10023_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
    ret = v4l2_int_device_register(&adw10023_int_device);
        // 进行排序
        if (d->type == v4l2_int_type_slave)
            sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
                 sizeof(struct v4l2_int_ioctl_desc),
                 &ioctl_sort_cmp, NULL);
}