linux-kernel - Re: [PATCH v4] gpio: driver for PrimeCell PL061 GPIO controller

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Message-ID: <20090610074839.GB27385@nokia.com>
Date:	Wed, 10 Jun 2009 10:48:39 +0300
From:	Felipe Balbi <felipe.balbi@...ia.com>
To:	ext Andrew Morton <akpm@...ux-foundation.org>
Cc:	Baruch Siach <baruch@...s.co.il>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dbrownell@...rs.sourceforge.net" <dbrownell@...rs.sourceforge.net>,
	"linux-arm-kernel@...ts.arm.linux.org.uk" 
	<linux-arm-kernel@...ts.arm.linux.org.uk>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>
Subject: Re: [PATCH v4] gpio: driver for PrimeCell PL061 GPIO controller

Hi,

On Wed, Jun 10, 2009 at 09:44:47AM +0200, ext Andrew Morton wrote:
> On Wed, 10 Jun 2009 10:22:31 +0300 Baruch Siach <baruch@...s.co.il> wrote:
> 
> > Hi Andrew,
> > 
> > > >  static unsigned int pl061_irq_startup(unsigned irq)
> > > >  {
> > > > -	int ret;
> > > > -
> > > > -	ret = gpio_request(irq_to_gpio(irq), "IRQ");
> > > > -	if (ret < 0) {
> > > > -		pr_warning("%s: warning: gpio_request(%d) returned %d\n",
> > > > -				__func__, irq_to_gpio(irq), ret);
> > > > -		return 0;
> > > > -	}
> > > > +	if (gpio_request(irq_to_gpio(irq), "IRQ") == 0)
> > > > +		pr_warning("%s: warning: GPIO%d has not been requested\n",
> > > > +				__func__, irq_to_gpio(irq));
> > > 
> > > This is wrong, isn't it?  gpio_request() returns 0 on success.
> > 
> > Russell said that gpio configuration is the responsibility of the platform 
> > code. Here I just warn when the gpio has not been requested, and thus 
> > gpio_request() succeeds. I'll add a comment.
> 
> OK.
> 
> If the gpio_request() accidentally succeeded, should we gpio_free() the
> result here?
> 
> Should the gpio core provide a primitive to check that a gpio has been
> properly requested rathe rthan open-coding it here?

how about passing a setup() and cleanup() pointers via platform_data to the driver ?

Then, during probe(), the driver calls setup() which would
gpio_request() and during remove() it calls cleanup() to gpio_free();

would that be ok ?

-- 
balbi
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