Re: [RFC PATCH] gpiolib: add gpio get direction support

From: Mathias Nyman
Date: Tue Oct 23 2012 - 07:04:05 EST

On 10/23/2012 01:23 AM, Linus Walleij wrote:
On Mon, Oct 22, 2012 at 3:44 PM, Mathias Nyman
<mathias.nyman@xxxxxxxxxxxxxxx> wrote:

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

Thought I'd do it the same was as gpio_direction_output() and gpio_direction_input(), but if there is no need for getting the direction outside gpiolob then it can be skipped. Main motivation was to get correct direction values in debug and sysfs after boot.

gpiolib currently uses cached values of gpio_direction_output/input() in sysfs. If the .get_direction callback exists it is used to refresh the cached values.

I'll write a new patch without the public gpio_get_direction().

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