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    SubjectRe: DT GPIO numbering?
    On 08/05/2012 04:06 AM, Linus Walleij wrote:
    > On Wed, Aug 1, 2012 at 5:22 PM, Johannes Stezenbach <> 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 :-/

    I can't comment on the sysfs-vs-dev interface location, but I don't
    think it addresses Johannes' issue; finding out which GPIO IDs are
    provided by which devices.

    Perhaps in each device's sysfs node, there should be some information
    re: which GPIO range it provides. Right now, perhaps a text file with
    the GPIO base it it. With the new /dev interface you mention above,
    perhaps a symlink to the /dev file, or a file containing the /dev file's
    major/minor number. Or, is there such a thing already (other than
    debugfs's gpio file).

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