From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marek Vasut <marex@denx.de>
Date: Thu, 20 Jun 2013 01:51:12 +0200
Subject: [U-Boot] gpio: Question about gpio_set_value() implementation
	in spear_gpio.c
In-Reply-To: <CAP9ODKriDTSoe3MwiBSNFaWOm+wxxwreXMKyA87Xe8==h1=mnQ@mail.gmail.com>
References: <1371649453.2126.2.camel@phoenix>
	<CAP9ODKriDTSoe3MwiBSNFaWOm+wxxwreXMKyA87Xe8==h1=mnQ@mail.gmail.com>
Message-ID: <201306200151.12602.marex@denx.de>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

Dear Otavio Salvador,

> On Wed, Jun 19, 2013 at 10:44 AM, Axel Lin <axel.lin@ingics.com> wrote:
> > Current code looks strange because no matter the value argument is 0 or 1
> > it always calls
> > 
> >         writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
> > 
> > And then gpio_get_value() always return 1.
> > 
> > I'm wondering if it needs to be fixed, something like below change:
> > 
> > diff --git a/drivers/gpio/spear_gpio.c b/drivers/gpio/spear_gpio.c
> > index d3c728e..8878608 100644
> > --- a/drivers/gpio/spear_gpio.c
> > +++ b/drivers/gpio/spear_gpio.c
> > @@ -52,7 +52,10 @@ int gpio_set_value(unsigned gpio, int value)
> > 
> >  {
> >  
> >         struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
> > 
> > -       writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
> > +       if (value)
> > +               writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
> > +       else
> > +               writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
> > 
> >         return 0;
> >  
> >  }
> 
> writel(value << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
> 
> Should do no? This would avoid the if block.

No, you need clrbits_le32() to unset the GPIO

Best regards,
Marek Vasut