linux-kernel - Re: [PATCH v4] Input: gpio_keys: Add level trigger support for GPIO keys

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Message-ID: <CAHp75VdOLUF8UQYkuK0Pmi9uefJgk4oZVBerFoBObOXM7zpCUQ@mail.gmail.com>
Date:   Thu, 1 Mar 2018 15:59:11 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Baolin Wang <baolin.wang@...aro.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stephen lu <lumotuwe@...il.com>,
        Arvind Yadav <arvind.yadav.cs@...il.com>,
        Joseph Lo <josephl@...dia.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-input <linux-input@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v4] Input: gpio_keys: Add level trigger support for GPIO keys

On Thu, Mar 1, 2018 at 2:37 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Thu, Mar 1, 2018 at 1:09 PM, Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
>> On Thu, Mar 1, 2018 at 9:36 AM, Baolin Wang <baolin.wang@...aro.org> wrote:
>>> On some platforms (such as Spreadtrum platform), the GPIO keys can only
>>> be triggered by level type. So this patch introduces one trigger_type to
>>> indicate if the button's interrupt type is level trigger or edge trigger.
>>
>>>                         button->irq =
>>>                                 irq_of_parse_and_map(to_of_node(child), 0);
>>
>> AFAIU, 0 means NO_IRQ, thus,
>>
>>> +                       if (button->irq)
>>> +                               button->trigger_type =
>>> +                                       irq_get_trigger_type(button->irq);
>>
>> irq_get_trigger_type(NO_IRQ) should return 0.
>>
>> Therefore, if (button->irq) is redundant.
>> Did I miss anything?
>
> "irq_of_parse_and_map(to_of_node(child), 0);" is the first interrupt. A
> more common way to express the same thing in modern drivers is
> 'platform_get_irq(pdev, 0)'.

Yes, though I'm talking about _returned_ value.

> However, there is one more thing I'm missing: with my suggestion
> of emulating edge-triggered interrupts in the irqchip/gpio driver, the
> trigger type here should also be 'IRQF_TRIGGER_RISING |
> IRQF_TRIGGER_FALLING' in the DT description, so I don't think
> we need to change the gpio-keys driver at all, just the gpio driver.

Sounds even better.

-- 
With Best Regards,
Andy Shevchenko