what is the current/ongoing state of userspace access to GPIO?

Robert P. J. Day rpjday at crashcourse.ca
Wed May 24 07:58:19 EDT 2017

  ashamed to admit, i haven't been keeping up with this, so AIUI, the
GPIO sysfs interface is deprecated, replaced with character device
files (/dev/gpiochip*) to allow access to GPIO.

  first, i find it curious that this is a move away from sysfs access
to using ioctl(), since i had always thought ioctls were massively
discouraged in new code. is there a document that goes through the
rationale for this change?

  and i notice under Documentation/ABI/ that sysfs-gpio is listed
under "obsolete", while gpio-cdev is listed under "testing". this
seems inconsistent -- how can one be obsolete while the other be
categorized as testing? that just seems strange.

  in any event, is the /dev/gpiochip* interface the recommended
interface now? thanks.



Robert P. J. Day                                 Ottawa, Ontario, CANADA

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