linux-kernel - Re: [PATCH 1/1] gpio: core: Decouple open drain/source flag with active low/high

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Message-ID: <CAHp75Ver7n=Xoer0YzA0sVVrcXKOB1bDz0ygSm0V0YoyYbe3pg@mail.gmail.com>
Date:   Thu, 6 Apr 2017 19:10:38 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Laxman Dewangan <ldewangan@...dia.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Frank Rowand <frowand.list@...il.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/1] gpio: core: Decouple open drain/source flag with
 active low/high

On Thu, Apr 6, 2017 at 4:35 PM, Laxman Dewangan <ldewangan@...dia.com> wrote:
> Currently, the GPIO interface is said to Open Drain if it is Single
> Ended and active LOW. Similarly, it is said as Open Source if it is
> Single Ended and active HIGH.
>
> The active HIGH/LOW is used in the interface for setting the pin
> state to HIGH or LOW when enabling/disabling the interface.
>
> In Open Drain interface, pin is set to HIGH by putting pin in
> high impedance and LOW by driving to the LOW.
>
> In Open Source interface, pin is set to HIGH by driving pin to
> HIGH and set to LOW by putting pin in high impedance.
>
> With above, the Open Drain/Source is unrelated to the active LOW/HIGH
> in interface. There is interface where the enable/disable of interface
> is ether active LOW or HIGH but it is Open Drain type.
>
> Hence decouple the Open Drain with Single Ended + Active LOW and
> Open Source with Single Ended + Active HIGH.
>
> Adding different flag for the Open Drain/Open Source which is valid
> only when Single ended flag is enabled.

>         if (single_ended) {
> -               if (active_low)
> +               if (open_drain)

This breaks ACPI case, right?

-- 
With Best Regards,
Andy Shevchenko