when to return -EOPNOTSUPP in _ioctl in a driver

[devendra.aaru]

Hi all,

While going through some code, i have found a place in which we do return,
-EOPNOTSUPP in an ioctl and the code of ioctl does just this one.


static int drv_ioctl(.. *fops, ...)
{
          return -EOPNOTSUPP;
}


do we actually need to specify a pointer to the ioctl callback, if the
driver doesn't support ioctl?