linux-kernel - Re: [PATCH v1 2/3] Documentation: gpio: Add a section on what to return in ->get() callback

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Date:   Wed, 30 Nov 2022 18:22:42 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Marc Zyngier <maz@...nel.org>, linux-gpio@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH v1 2/3] Documentation: gpio: Add a section on what to
 return in ->get() callback

On Wed, Nov 30, 2022 at 05:14:38PM +0100, Hans de Goede wrote:
> On 11/30/22 17:12, Hans de Goede wrote:
> > On 11/30/22 16:55, Andy Shevchenko wrote:

...

> > IHMO the rules for get() should simply be:
> > 
> > 1. Device has an input buffer:
> >    Return input-buffer value for the pin.
> > 
> > 2. Devices does not have an input buffer:
> >    Return last set output-buffer value
> 
> Quick correction device should be pin here, because it
> if there is an input buffer or not can differ per pin.
> So IHMO the rules for get() should simply be:
> 
> 1. pin has an input buffer:
>    return input-buffer value for the pin.
> 
> 2. pin does not have an input buffer:
>    return the value last set for the pin's output-buffer

"pin" misleads here. The "pin" can be in native function which may have not be
even connected to GPIO buffers. There are different hardware topologies.

So, no, not a "pin".

-- 
With Best Regards,
Andy Shevchenko