linux-kernel - Re: [PATCH 7/7 v2] gpio: dwapb: use d->mask instead od BIT(bit)

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Date:	Tue, 25 Mar 2014 14:25:16 -0700
From:	Joe Perches <joe@...ches.com>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	Alexandre Courbot <gnurou@...il.com>, atull@...era.com,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dinguyen@...era.com, delicious.quinoa@...il.com
Subject: Re: [PATCH 7/7 v2] gpio: dwapb: use d->mask instead od BIT(bit)

On Tue, 2014-03-25 at 22:18 +0100, Sebastian Andrzej Siewior wrote:
> d->mask contains exact the same information as BIT(bit) so we could save
> a few cycles here.

I think you actually lose a few cycles here as
the pointer has to be dereferenced for each use.

> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
[]
> @@ -171,24 +170,24 @@ static int dwapb_irq_set_type(struct irq_data *d, u32 type)
>  
>  	switch (type) {
>  	case IRQ_TYPE_EDGE_BOTH:
> -		level |= BIT(bit);
> -		dwapb_toggle_trigger(gpio, bit);
> +		level |= d->mask;
> +		dwapb_toggle_trigger(gpio, d->hwirq);
>  		break;
>  	case IRQ_TYPE_EDGE_RISING:
> -		level |= BIT(bit);
> -		polarity |= BIT(bit);
> +		level |= d->mask;
> +		polarity |= d->mask;
>  		break;
>  	case IRQ_TYPE_EDGE_FALLING:
> -		level |= BIT(bit);
> -		polarity &= ~BIT(bit);
> +		level |= d->mask;
> +		polarity &= ~d->mask;
>  		break;
>  	case IRQ_TYPE_LEVEL_HIGH:
> -		level &= ~BIT(bit);
> -		polarity |= BIT(bit);
> +		level &= ~d->mask;
> +		polarity |= d->mask;
>  		break;
>  	case IRQ_TYPE_LEVEL_LOW:
> -		level &= ~BIT(bit);
> -		polarity &= ~BIT(bit);
> +		level &= ~d->mask;
> +		polarity &= ~d->mask;
>  		break;
>  	}
>  



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