Re: [PATCH V3 04/12] misc: xilinx_sdfec: Add open, close and ioctl

From: Arnd Bergmann
Date: Sat May 04 2019 - 10:35:57 EST

On Thu, May 2, 2019 at 1:23 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> On Sat, Apr 27, 2019 at 11:04:58PM +0100, Dragan Cvetic wrote:
> > Add char device interface per DT node present and support
> > file operations:
> > - open(),
> > - close(),
> > - unlocked_ioctl(),
> > - compat_ioctl().
> Why do you need compat_ioctl() at all? Any "new" driver should never
> need it. Just create your structures properly.

The function he added was the version that is needed when the structures
are compatible. I submitted a series to add a generic 'compat_ptr_ioctl'
implementation that would save a few lines here doing the same thing,
but it's not merged yet.

Generally speaking, every driver that has a .ioctl() function should also
have a .compat_ioctl(), and ideally it should be exactly this trivial