Messages in this thread | | | Date | Wed, 16 Jul 2014 23:37:48 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH] gpio: Add support for GPIOF_ACTIVE_LOW to gpio_request_one |
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On 07/16/2014 11:09 PM, Alexandre Courbot wrote: > On Thu, Jul 17, 2014 at 8:11 AM, Guenter Roeck <linux@roeck-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@roeck-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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