DT GPIO numbering?
Linus Walleij
linus.walleij at linaro.org
Sun Aug 5 20:06:03 EST 2012
On Wed, Aug 1, 2012 at 5:22 PM, Johannes Stezenbach <js at sig21.net> wrote:
> I'm currently learning how Linux devicetree support works,
> here is one question I couldn't find an answer for.
>
> I understand that within the devicetree GPIOs are referenced by phandle,
> thus the numbers are irrelevant. However, in sysfs the number is
> what is used to access the GPIO, e.g. for debugging or
> blinkenlight apps. How does this fit together?
I think it simply does not fit together.
Grant & me has been claiming the GPIO sysfs interface is a bit
crazy from time to time.
My long-term plan would be to replace it with /dev/gpio/gpioN
device nodes per-gpiochip and use ioctl etc to control these
beasts instead. However one does not do that overnight,
and my life is too busy, and other refactorings also need to
happen :-/
Yours,
Linus Walleij
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