linux-kernel - Re: [PATCH v3] Input: gpio_keys: Add level trigger support for GPIO keys

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Message-ID: <CAMz4kuLNbsZjDPW19V96yL3DzY-bJsjRR=o+w0x4PGyxZFZ0dg@mail.gmail.com>
Date:   Thu, 1 Mar 2018 15:35:23 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        gregkh <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>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        DTML <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 v3] Input: gpio_keys: Add level trigger support for GPIO keys

On 28 February 2018 at 22:44, Arnd Bergmann <arnd@...db.de> wrote:
> On Wed, Feb 28, 2018 at 1:44 PM, 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 property to
>> indicate if the GPIO trigger type is level trigger or edge trigger.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>> ---
>> Changes since v2:
>>  - Use 'interrupt' property to indicate the irq type.
>>
>> Changes since v1:
>>  - Diable the GPIO irq until reversing the GPIO level type.
>
> I've looked at your patch in more detail now, and given it a bit more thought.
>
> I wonder if you could move that logic into your gpiochip/irqchip driver instead.
> It seems that what you do in the gpio-keys driver is to emulate edge triggered
> behavior on a level triggered irqchip.
>
> If you put the same logic into the gpio driver, you could simply make it
> pretend to support an edge trigger on both edges and call into the interrupt
> handler whenever the state changes.
>

That is really a good suggestion, which can avoid duplicate level
reverse logic in different drivers. So this patch can be simplified
just adding one trigger_type to indicate the interrupt type (not
always edge trigger). Thanks for your suggestion.

-- 
Baolin.wang
Best Regards