Messages in this thread | | | Date | Tue, 23 Oct 2012 00:23:49 +0200 | Subject | Re: [RFC PATCH] gpiolib: add gpio get direction support | From | Linus Walleij <> |
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On Mon, Oct 22, 2012 at 3:44 PM, Mathias Nyman <mathias.nyman@linux.intel.com> wrote:
> Add gpio_get_direction() for checking the current direction of a gpio. > Returns 1 for input, 0 for output, or negative error. > Gpio drivers need to set the gpio_chip .get_direction callback for this > functionality, otherwise gpio_get_direction() returns error.
OK...
> If the .get_direction callback is set, then gpiolib will use it > for showing correct gpio direction in sysfs and debug. If not set > then it will work the old way; e.g. guessing everything is input > until direction is set.
If the driver cannot report the direction setting you *could* cache the result of all calls to gpio_direction_output() and gpio_direction_input() somewhere. But I don't know if it's a good idea.
Anyway, if the callback is only called internally in the GPIOlib why are you making the function public to the entire kernel like this?
> include/asm-generic/gpio.h > +extern int gpio_get_direction(unsigned gpio);
> include/linux/gpio.h > +static inline int gpio_get_direction(unsigned gpio) > +{ > + return -ENOSYS; > +} > +
Yours, Linus Walleij
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