linux-kernel - Re: [PATCH] gpiolib: Add gpio_detect, gpio_debounce and gpio_alt

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Message-ID: <20090615125025.GB19873@fluff.org.uk>
Date:	Mon, 15 Jun 2009 13:50:25 +0100
From:	Ben Dooks <ben-linux@...ff.org>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Ben Dooks <ben-linux@...ff.org>, Alek Du <alek.du@...el.com>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpiolib: Add gpio_detect, gpio_debounce and
	gpio_alt_func features to GPIOLIB

On Mon, Jun 15, 2009 at 11:02:53AM +0100, Mark Brown wrote:
> On Mon, Jun 15, 2009 at 10:50:23AM +0100, Ben Dooks wrote:
> > On Mon, Jun 15, 2009 at 05:15:02PM +0800, Alek Du wrote:
> 
> > > * gpio_alt_func is to set pin as alternative function or GPIO.
> 
> > gpio_alt_func is feature creep, I don't really belive this is the
> > best place to put it as it will be difficult to actually make this
> > generic for all gpio platforms.
> 
> Since the proposed API just passes a value through to the driver for the
> GPIO chip it looks generic enough - each chip can define whatever set of
> constants it likes.  I'd expect a large proportion of driver specific
> APIs would end up just the same.
> 
> Given the number of manufacturers that don't use a separate term like
> the PXA MFP for the alternative functions of their GPIOs it makes sense
> to have a gpiolib API for this.  Without one you end up having each
> driver needing to add its own API, and since the pins are just referred
> to as GPIOs in the documentation the API will have that in the name and
> look like it ought to be connected with gpiolib.

Yes, however I can see some horrible problems ahead as soon as people
try and then try and standardise the values passed through this. The
GPIO API was meant to be a lightweight way of allowing drivers at
GPIOs, now everyone seems to want to push whatever they feel like in.

-- 
Ben (ben@...ff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'
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