linux-kernel - RE: [PATCH] gpio: add flags to export GPIOs when requesting

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Message-ID: <74CDBE0F657A3D45AFBB94109FB122FF1740805F1A@HQMAIL01.nvidia.com>
Date:	Tue, 15 Nov 2011 15:32:34 -0800
From:	Stephen Warren <swarren@...dia.com>
To:	Denis Kuzmenko <linux@...onet.org.ua>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Dong Aisheng <dong.aisheng@...aro.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: RE: [PATCH] gpio: add flags to export GPIOs when requesting

Denis Kuzmenko wrote at Tuesday, November 15, 2011 4:05 PM:
> Hi Wolfram,
> On 11/16/2011 12:44 AM, Wolfram Sang wrote:
> > Introduce new flags to automatically export GPIOs when using the convenience
> > functions gpio_request_one() or gpio_request_array(). This eases support for
> > custom boards where lots of GPIOs need to be exported for customer
> > applications.
> 
> Adding GPIO maintainer Grant Likely to CC.
> 
> > +#define GPIOF_EXPORT		(1 << 2)
> > +#define GPIOF_EXPORT_CHANGEABLE	(1 << 3)
> > +#define GPIOF_EXPORT_DIR_FIXED	(GPIOF_EXPORT)
> > +#define GPIOF_EXPORT_DIR_CHANGEABLE (GPIOF_EXPORT | GPIOF_EXPORT_CHANGEABLE)
> 
> Maybe, it's better to write like this:
> 
> #define GPIOF_EXPORT			(1 << 2)
> #define GPIOF_EXPORT_DIR_CHANGEABLE	(3 << 2)

Then you won't have a single flag to check if the dir is changeable.

Personally, I'd go for the two single-bit flags, and force boards to OR
them together if they want the GPIO exported and with a changeable
direction; just get rid of the two _DIR_ flags. That said, Wolfram's
patch seems to follow the conventions already in the file.

Dong Aisheng posted patch "gpio: introduce gpio_export_array to ease
export for gpio arrays". Which should we pick; it doesn't seem like we
need both mechanisms.

-- 
nvpublic

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