linux-kernel - Re: [PATCH v1 2/4] gpio: add parameter to allow the use named gpios

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Date:	Wed, 21 Jan 2015 22:44:49 +0100
From:	Olliver Schinagl <oliver@...inagl.nl>
To:	Alexandre Courbot <gnurou@...il.com>,
	Olliver Schinagl <oliver+list@...inagl.nl>
CC:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Robin Gong <b38343@...escale.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Aaron Lu <aaron.lu@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Grant Likely <grant.likely@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Alexander Shiyan <shc_work@...l.ru>,
	Jingoo Han <jg1.han@...sung.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux Input <linux-input@...r.kernel.org>,
	"linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>
Subject: Re: [PATCH v1 2/4] gpio: add parameter to allow the use named gpios

Hey Alexandre,

On 01/19/2015 05:04 AM, Alexandre Courbot wrote:
> On Wed, Jan 7, 2015 at 6:08 PM, Olliver Schinagl
> <oliver+list@...inagl.nl> wrote:
>> From: Olliver Schinagl <oliver@...inagl.nl>
>>
>> The gpio binding document says that new code should always use named
>> gpios. Patch 40b73183 added support to parse a list of gpios from child
>> nodes, but does not make it possible to use named gpios. This patch adds
>> the con_id property and implements it is done in gpiolib.c, where the
>> old-style of using unnamed gpios still works.
> This is absolutely correct - thanks for spotting this.
>
> <snip>
> ... since it looks like this part has been mostly copy/pasted from
> of_find_gpio(), can you add another patch that fixes it there as well?
Yeah, since it has the same functionality, i copy pasted it. Wasn't sure 
if it was worth to macro it or anything. I've sent a v2 with that patch 
added to the mix :)
>
> Also in the case of ACPI this will prove to be an incomplete lookup
> since acpi_find_gpio() has an additional fallback if the named lookup
> fails.
I'm not very familiar (or at all) how ACPI falls into all of this, I'm 
just starting to get a hang of the DT, but since this is how the dts is 
being parsed, where is the relation here? Or did I misunderstand?
>
> In that respect, I wonder if it would not be better for
> devm_get_gpiod_from_child() to call of_find_gpio() and
> acpi_find_gpio() (after making them non-static) followed by
> gpiod_request() instead of calling fwnode_get_named_gpiod(). But in
> that case it will have to do the OF/ACPI handling by itself.
>
> I'm not really sure about which way is better. I'd appreciate if you
> could give a thought to a possible refactoring that would improve the
> situation ; otherwise feel free to ignore what I have written above
> and to duplicate the property name building code.
I'm afraid I'm a little too inexperienced to follow exactly what you say ;)

Olliver

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