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Is there a bug in the sysfs gpio read implementation of linux kernel 3.14.28 for iMX6?

Question asked by joerutledge on Nov 25, 2015
Latest reply on Dec 4, 2015 by CarlosCasillas

I've got a Fido Yocto build generating a 3.14.28 Linux kernel with GPIO sysfs support for my iMX6Q. When controlling the GPIOs vis sysfs I get expected behaviour on a write but unexpected behaviour on a read. Having set the direction appropriately reading from "value" in sysfs I get 0 returned for an unset GPIO but I get a 32 bit value with just the bit set representing the gpio within the bank for a "set" value. This seems to be against the kernel documentation implying a 0 or 1 response for the GPIO.

 

Is this a known bug or have I misconfigured something or have I just misinterpreted expected behaviour?

 

Many thanks,

 

Joe

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