linux-kernel - Re: [PATCH v5] gpio: driver for PrimeCell PL061 GPIO controller

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Message-ID: <20090616042008.GA2794@jasper.tkos.co.il>
Date:	Tue, 16 Jun 2009 07:20:09 +0300
From:	Baruch Siach <baruch@...s.co.il>
To:	David Brownell <david-b@...bell.net>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-arm-kernel@...ts.arm.linux.org.uk,
	Russell King - ARM Linux <linux@....linux.org.uk>
Subject: Re: [PATCH v5] gpio: driver for PrimeCell PL061 GPIO controller

Hi David,

Thank you very much for your review.

On Mon, Jun 15, 2009 at 04:29:11PM -0700, David Brownell wrote:
> On Thursday 11 June 2009, Baruch Siach wrote:
> > +static unsigned int pl061_irq_startup(unsigned irq)
> > +{
> > +       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));
> 
> No, that's the responsibility of whoever is setting this up.

The gpio_request() here is only for warning. It is expected to fail. Should I 
remove it? Shouldn't there be an is_gpio_requested() as part of gpiolib?

> Normally, platform setup code would request the GPIO since it's
> being dedicated to some task on the board ... and then pass the
> gpio_to_irq() value as a device resource, or maybe the GPIO itself
> (if the driver had to deal with GPIOs per se).
> 
> Also, irq_to_gpio() can be problematic in some systems; avoid it.

I use irq_to_gpio() extensively to implement the enable/disable etc. methods 
of irq_chip. Is there a way to implement them without irq_to_gpio()?

> > +
> > +       pl061_irq_enable(irq);
> > +
> > +       return 0;
> > +}
> 
> Remove that gpio_request(), and the irq_to_gpio(), and you get:
> 
> Acked-by: David Brownell <dbrownell@...rs.sourceforge.net>

Thanks,

Baruch

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