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Date: Tue, 7 Sep 2010 16:44:55 -0700 (PDT)
From: David Brownell <david-b@pacbell.net>
Subject: Re: [PATCH] pio: add arch specific gpio_is_valid() function
To: Ryan Mallon <ryan@bluewatersys.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "avictor.za@gmail.com" <avictor.za@gmail.com>,
        Eric Miao <eric.y.miao@gmail.com>,
        Nicolas Ferre <nicolas.ferre@atmel.com>, linux-kernel@vger.kernel.org,
        bn@niasdigital.com,
        Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
        linux-arm-kernel@lists.infradead.org
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--- On Tue, 9/7/10, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > 
> >      device->output_pin = -EINVAL;
> 
> gpio numbers are unsigned in the rest of the API

Minor goof; should have been "int" everywhere,
as implied by the references to negative numbers
in the docs... negatives not used internally, but
preserved for external use (as above).


> 
> It's unfortunate that 0 was used for a GPIO

Intentional:  board schematics and chip docs can
easily match up to Linux this way.  What would be
unfortunate is needing to map hardware docs into
software ones all the time -- error prone.

When the API is used correctly, it's not an issue.