linux-kernel - Re: [PATCH v2 2/2] gpio-langwell: implement irq shutdown interface

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Date:	Sat, 22 Dec 2012 10:12:44 +0000
From:	Grant Likely <grant.likely@...retlab.ca>
To:	David Cohen <david.a.cohen@...el.com>
Cc:	linux-kernel@...r.kernel.org, alan@...ux.intel.com,
	"Li, Ning" <ning.li@...el.com>,
	David Cohen <david.a.cohen@...el.com>
Subject: Re: [PATCH v2 2/2] gpio-langwell: implement irq shutdown interface

On Thu, 20 Dec 2012 14:45:52 -0800, David Cohen <david.a.cohen@...el.com> wrote:
> From: "Li, Ning" <ning.li@...el.com>
> 
> Disable falling/rising edge detection during irq shutdown operation.

Why? (A commit description should also say why a change is needed. Not
just what it does)

g.

> 
> Signed-off-by: David Cohen <david.a.cohen@...el.com>
> Signed-off-by: Li, Ning <ning.li@...el.com>
> ---
>  drivers/gpio/gpio-langwell.c |   21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/gpio/gpio-langwell.c b/drivers/gpio/gpio-langwell.c
> index 2be69fe..10cc520 100644
> --- a/drivers/gpio/gpio-langwell.c
> +++ b/drivers/gpio/gpio-langwell.c
> @@ -225,11 +225,32 @@ static void lnw_irq_mask(struct irq_data *d)
>  {
>  }
>  
> +static void lnw_irq_shutdown(struct irq_data *d)
> +{
> +	struct lnw_gpio *lnw = irq_data_get_irq_chip_data(d);
> +	u32 gpio = irqd_to_hwirq(d);
> +	unsigned long flags;
> +	u32 value;
> +	void __iomem *grer = gpio_reg(&lnw->chip, gpio, GRER);
> +	void __iomem *gfer = gpio_reg(&lnw->chip, gpio, GFER);
> +
> +	spin_lock_irqsave(&lnw->lock, flags);
> +
> +	/* Disable falling/rising edge detection */
> +	value = readl(grer) & ~BIT(gpio % 32);
> +	writel(value, grer);
> +	value = readl(gfer) & ~BIT(gpio % 32);
> +	writel(value, gfer);
> +
> +	spin_unlock_irqrestore(&lnw->lock, flags);
> +};
> +
>  static struct irq_chip lnw_irqchip = {
>  	.name		= "LNW-GPIO",
>  	.irq_mask	= lnw_irq_mask,
>  	.irq_unmask	= lnw_irq_unmask,
>  	.irq_set_type	= lnw_irq_type,
> +	.irq_shutdown	= lnw_irq_shutdown,
>  };
>  
>  static DEFINE_PCI_DEVICE_TABLE(lnw_gpio_ids) = {   /* pin number */
> -- 
> 1.7.10.4
> 

-- 
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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