linux-kernel - Re: [PATCH v9 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES

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Message-ID: <CAMRc=Mc7O2FGT3ZHLbNozQpK6bTei=Y0DLrvDSViqG49xUY4Ew@mail.gmail.com>
Date:   Thu, 24 Sep 2020 16:29:06 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Kent Gibson <warthog618@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v9 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL
 and GPIO_V2_LINE_GET_VALUES_IOCTL

On Wed, Sep 23, 2020 at 1:12 PM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>

[snip!]

>
> > +       /* Bias requires explicit direction. */
> > +       if ((flags & GPIO_V2_LINE_BIAS_FLAGS) &&
> > +           !(flags & GPIO_V2_LINE_DIRECTION_FLAGS))
> > +               return -EINVAL;
>
> Okay, since this is strict we probably may relax it in the future if
> it will be a use case.
> ...
>
> > +       /* Only one bias flag can be set. */
>
> Ditto. (Some controllers allow to set both simultaneously, though I
> can't imagine good use case for that)
>

This is an abstraction layer. Only because some controllers allow
this, doesn't mean we should reflect this in our abstraction layer -
especially if we know well that this has no purpose.

Bartosz