linux-kernel - Re: [PATCH v16 10/14] gpio: 74x164: Utilize the for_each_set

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Date:   Mon, 7 Oct 2019 11:24:27 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     linus.walleij@...aro.org, bgolaszewski@...libre.com,
        akpm@...ux-foundation.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux@...musvillemoes.dk, yamada.masahiro@...ionext.com,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        geert@...ux-m68k.org, preid@...ctromag.com.au, lukas@...ner.de,
        sean.nyekjaer@...vas.dk, morten.tiljeset@...vas.dk,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: Re: [PATCH v16 10/14] gpio: 74x164: Utilize the for_each_set_clump8
 macro

On Sun, Oct 06, 2019 at 11:11:07AM -0400, William Breathitt Gray wrote:
> Replace verbose implementation in set_multiple callback with
> for_each_set_clump8 macro to simplify code and improve clarity.

I can test it somewhat later.

> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Cc: Geert Uytterhoeven <geert+renesas@...der.be>
> Cc: Phil Reid <preid@...ctromag.com.au>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>
> ---
>  drivers/gpio/gpio-74x164.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c
> index e81307f9754e..05637d585152 100644
> --- a/drivers/gpio/gpio-74x164.c
> +++ b/drivers/gpio/gpio-74x164.c
> @@ -6,6 +6,7 @@
>   *  Copyright (C) 2010 Miguel Gaio <miguel.gaio@...xo.com>
>   */
>  
> +#include <linux/bitops.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/gpio/driver.h>
>  #include <linux/module.h>
> @@ -72,20 +73,18 @@ static void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask,
>  				    unsigned long *bits)
>  {
>  	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
> -	unsigned int i, idx, shift;
> -	u8 bank, bankmask;
> +	unsigned long offset;
> +	unsigned long bankmask;
> +	size_t bank;
> +	unsigned long bitmask;
>  
>  	mutex_lock(&chip->lock);
> -	for (i = 0, bank = chip->registers - 1; i < chip->registers;
> -	     i++, bank--) {
> -		idx = i / sizeof(*mask);
> -		shift = i % sizeof(*mask) * BITS_PER_BYTE;
> -		bankmask = mask[idx] >> shift;
> -		if (!bankmask)
> -			continue;
> +	for_each_set_clump8(offset, bankmask, mask, chip->registers * 8) {
> +		bank = chip->registers - 1 - offset / 8;
> +		bitmask = bitmap_get_value8(bits, offset) & bankmask;
>  
>  		chip->buffer[bank] &= ~bankmask;
> -		chip->buffer[bank] |= bankmask & (bits[idx] >> shift);
> +		chip->buffer[bank] |= bitmask;
>  	}
>  	__gen_74x164_write_config(chip);
>  	mutex_unlock(&chip->lock);
> -- 
> 2.23.0
> 

-- 
With Best Regards,
Andy Shevchenko