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Date: Wed, 16 Jul 2014 23:37:48 -0700 From: Guenter Roeck <linux@...ck-us.net> To: Alexandre Courbot <gnurou@...il.com> 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 07/16/2014 11:09 PM, Alexandre Courbot wrote: > 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. > One can use gpio_request_one() to export a gpio pin to user space from the kernel. That code path does use the flag, as you point out yourself above. One could also argue that the integer gpio API _should_ support this as well, but that is a different question. Guenter >> >> 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 >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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