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References: <002e01d5ea82$ac0e8b20$042ba160$@adrianschmutzler.de>
In-Reply-To: <002e01d5ea82$ac0e8b20$042ba160$@adrianschmutzler.de>
From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date: Sun, 23 Feb 2020 22:28:43 +0100
Message-ID: <CAFBinCDCCoFrmKBCovCVBVPz3gdRza3jZ7JMh+rLpkjCeNfw4g@mail.gmail.com>
Subject: Re: [OpenWrt-Devel] gpio-export,output and GPIO_ACTIVE_*
To: mail@adrianschmutzler.de
Cc: openwrt-devel@lists.openwrt.org
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Hi Adrian,

On Sun, Feb 23, 2020 at 8:52 PM <mail@adrianschmutzler.de> wrote:
>
> Hi,
>
> when defining gpio-export nodes, I'm never really sure about how the values for "gpio-export,output" and GPIO_ACTIVE_HIGH/LOW in gpios have to be set up correctly in relation to each other.
>
> I also was not able to retrieve a particular system in how this is set up currently (for different devices).
>
> It would be nice if somebody could elaborate this to me (I've found several shorter explanations in the PR comments throughout GitHub, but they unfortunately were never comprehensive.)
I don't know about gpio-export

> (And I assume the same logic will apply to gpio-hogs with output-low/high and gpios parameter?)
for gpio-hog there is documentation inside the kernel sources:
Documentation/devicetree/bindings/gpio/gpio.txt

I don't know why there are output-low, output-high, input properties
and if they are optional (meaning for example output-high can be
omitted when setting GPIO_ACTIVE_HIGH). when in doubt, ask on the
linux-gpio mailing-list


Regards
Martin

]