linux-kernel - Re: [RFC 4/4] iio: trigger: add GPIO trigger

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Date:   Mon, 20 Feb 2017 17:24:16 +0100
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>, <linux@...linux.org.uk>,
        <robh+dt@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <linux-iio@...r.kernel.org>, <mark.rutland@....com>,
        <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>,
        <knaack.h@....de>, <pmeerw@...erw.net>,
        <benjamin.gaignard@...aro.org>, <benjamin.gaignard@...com>,
        <linus.walleij@...aro.org>
Subject: Re: [RFC 4/4] iio: trigger: add GPIO trigger

On 02/18/2017 08:19 PM, Jonathan Cameron wrote:
> On 17/02/17 16:16, Lars-Peter Clausen wrote:
>> On 02/17/2017 05:03 PM, Fabrice Gasnier wrote:
>>> GPIOs can be used to generate triggers for any IIO device.
>>> Introduce generic GPIO trigger driver. It offers some options
>>> to tune polarity (e.g. rising/falling edge), and label so trigger
>>> name may be customized.
>>> By default, gpio triggers will be named gpiotrigX, where X is gpio
>>> number as returned by desc_to_gpio() call.
>>> Rising edge is selected if polarity isn't set.
>>
>> If you want to use the GPIO only as an interrupt, just use it as an
>> interrupt directly, no need to go the route via the GPIO.
> Absolutely.  The majority of the bindings will then just become standard
> interrupt bindings and will be effectively handled for you.
>
> Please work to extend the existing interrupt trigger driver rather than adding
> this new one.  That one actually started as a gpio trigger then got
> generalised into a interrupt trigger later so lets not do that again ;)

Hi Lars, Jonathan

Ok, got it.
I'll drop this and focus on interrupt trigger, if this is worth having 
DT for it (e.g. patch 1 & 2 of this RFC).

BTW, I figured out there has been this patch a year ago, on interrupt 
trigger, to add device tree support:
http://www.spinics.net/lists/linux-iio/msg23126.html
Any reason why it hasn't found its way in ?

Thanks for reviewing,
Best Regards,
Fabrice

>
> Jonathan
>