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From:   Baolin Wang <baolin.wang@linaro.org>
Date:   Fri, 2 Mar 2018 11:10:31 +0800
Message-ID: <CAMz4ku+Ruz=O9NE4x+cm4tFXR+en7mKX4D0aP841qKrdRMMP6Q@mail.gmail.com>
Subject: Re: [PATCH v3] Input: gpio_keys: Add level trigger support for GPIO keys
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     Arnd Bergmann <arnd@arndb.de>, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        gregkh <gregkh@linuxfoundation.org>,
        stephen lu <lumotuwe@gmail.com>,
        Arvind Yadav <arvind.yadav.cs@gmail.com>,
        Joseph Lo <josephl@nvidia.com>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>
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On 2 March 2018 at 08:44, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> On Thu, Mar 01, 2018 at 03:35:23PM +0800, Baolin Wang wrote:
>> On 28 February 2018 at 22:44, Arnd Bergmann <arnd@arndb.de> wrote:
>> > On Wed, Feb 28, 2018 at 1:44 PM, Baolin Wang <baolin.wang@linaro.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@linaro.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.
>
> No, there is no need to add trigger type. The gpio-keys driver expects
> trigger with both edges, falling and rising. If your GPIO chip does not
> support it natively, you need to emulate edge trigger via level
> interrupts by reprogramming trigger from active low to active high and
> back on the fly. This should be done in the gpiochip/irqchip driver.
> There is no need to change gpio-keys driver.

Yes, you are right, It can work on my platform after modifying my GPIO
driver like you and Arnd's suggestion. Thanks for all your help.

-- 
Baolin.wang
Best Regards