From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= <clg@kaod.org>
Subject: Re: [PATCH] leds: pca955x: add GPIO support
Date: Tue, 23 May 2017 12:58:42 +0200
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To: Linus Walleij <linus.walleij@linaro.org>, Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>, Pavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, "linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Joel Stanley <joel@jms.id.au>
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On 05/23/2017 10:18 AM, Linus Walleij wrote:
> On Thu, May 11, 2017 at 10:23 PM, Jacek Anaszewski
> <jacek.anaszewski@gmail.com> wrote:
> 
>>> +Optional properties:
>>> +- gpio-controller: allows pins to be used as GPIOs.
> 
> Are these output-only? Then write something about that.

no. input is also supported.

>>> +- #gpio-cells: if present, must not be 0.
> 
> Must be present and must be <2>
> 
>>> +- gpio-base : base number of the pins used as GPIOs. If there are more
>>> +              than one, they should be contiguous. See 'type' property
>>> +              below.
> 
> NACK. Not in my life.

yes, indeed. this is useless. 
 
> Provide -1 in the Linux driver and use the ioctl() from userspace
> to look up your gpios. Add .names array to the gpiochip if necessary,
> define line names in the device tree for the board.
> 
> Consult tools/gpio/* for the modern way of using GPIOs.

OK. I wasn't aware of these.

Thanks,

C.