linux-kernel - Re: [PATCH] gpio: Add support for GPIOF_ACTIVE_LOW to gpio_request

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Message-ID: <CAAVeFuLtUpKKVWAvJ-bw_b36jYFhrzaWeswnJKyehbwn=6y+4Q@mail.gmail.com>
Date:	Thu, 17 Jul 2014 15:09:28 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] gpio: Add support for GPIOF_ACTIVE_LOW to gpio_request_one

On Thu, Jul 17, 2014 at 8:11 AM, Guenter Roeck <linux@...ck-us.net> wrote:
> The gpio include file and the gpio documentation declare and document
> GPIOF_ACTIVE_LOW as one of the flags to be passed to gpio_request_one
> and related functions. However, the flag is not evaluated or used.
>
> Check the flag in gpio_request_one and set the gpio internal flag
> FLAG_ACTIVE_LOW if it is set.

What is the point since the integer GPIO API has no clue of the
active-low status of a GPIO? It is only used by the gpiod and sysfs
interfaces.

>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  drivers/gpio/gpiolib.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 2ebc907..43d9e34 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1842,6 +1842,9 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
>         if (flags & GPIOF_OPEN_SOURCE)
>                 set_bit(FLAG_OPEN_SOURCE, &desc->flags);
>
> +       if (flags & GPIOF_ACTIVE_LOW)
> +               set_bit(FLAG_ACTIVE_LOW, &desc->flags);
> +
>         if (flags & GPIOF_DIR_IN)
>                 err = gpiod_direction_input(desc);
>         else
> --
> 1.9.1
>
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