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Date: Thu, 15 Nov 2007 08:35:42 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: David Brownell <david-b@pacbell.net>
cc: Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel list <linux-kernel@vger.kernel.org>,
       Florian Fainelli <florian.fainelli@telecomint.eu>,
       Haavard Skinnemoen <hskinnemoen@atmel.com>, Ingo Molnar <mingo@elte.hu>,
       Nick Piggin <nickpiggin@yahoo.com.au>
Subject: Re: [patch 2.6.24-rc2 1/3] generic gpio -- gpio_chip support
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On Wed, 14 Nov 2007, David Brownell wrote:

> On Wednesday 14 November 2007, Thomas Gleixner wrote:
> > struct gpio_desc {
> > 	   struct gpio_chip *chip;
> > 	   int pinoffset;
> > };
> 
> Eric Miao has a different notion of "gpio_desc" more analagous to
> the "irq_desc", so I'll not use that name for such a structure.
> 
> Let me call yours a "struct gpio_pin" instead -- purely for some
> discussion here.
>
> 
> There's been some desire for a "gpio_pin" struct for entirely
> different reasons ... as the identifiers passed into a slightly
> different type of GPIO programming interface.  So for example
> 
>   static inline void gpiopin_set_value(struct gpio_pin *p, int v)
>   {
> 	p->chip->set(p->chip, p->pinoffset, v);
>   }
> 
> One reason to be interested in gpio_chip is that it it would
> easily support interoperation between traditional GPIO ID schemes
> (numbered to match the SOC at the heart of a given board) and
> more dynamic ones that might be needed to use curiousities like
> a set of USB-to-GPIO adapters.

So can we please do this right from the beginning instead of adding a
new library first which suffers from bad design compromises.

    tglx