On Wed, Oct 23, 2013 at 05:49:06PM +0100, Stephen Warren wrote: > On 10/23/2013 02:42 PM, Jean-Christophe PLAGNIOL-VILLARD wrote: > ... > > For me gpio_get_value can return the value of a an output gpio but this need > > to be checked with LinusW > > That's certainly not true for all possible GPIO controllers; there are > at least some that can't read either: > > * The value of the physical wire, if the GPIO is configured as an output. > > * The value that the GPIO controller is driving as an output. My point originally was that since it's an output pin, you need to configure it as an output before you can use it. The way to do that in Linux is to call gpio_direction_output(). But that will automatically also force the output value to whatever you specify as the second parameter. I suppose that could be remedied by adding a separate function that doesn't set the value, but as Stephen points out, reading the value of an output pin may not be supported on all hardware. Thierry
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