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Message-ID: <CAK8P3a2EKXrg4amHDi5zVvOQ8AM+u6EAhBc=T8Hk_tU20xSV4w@mail.gmail.com>
Date: Sat, 4 May 2019 10:35:02 -0400
From: Arnd Bergmann <arnd@...db.de>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: Dragan Cvetic <dragan.cvetic@...inx.com>,
Michal Simek <michal.simek@...inx.com>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
DTML <devicetree@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Derek Kiernan <derek.kiernan@...inx.com>
Subject: Re: [PATCH V3 04/12] misc: xilinx_sdfec: Add open, close and ioctl
On Thu, May 2, 2019 at 1:23 PM Greg KH <gregkh@...uxfoundation.org> 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
version.
Arnd
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