[PATCH 1/2] Documentation/gpio.txt: Explain expected pinctrl interaction

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Feb 20 02:39:41 EST 2012

On Sun, Feb 19, 2012 at 11:27:42PM -0700, Stephen Warren wrote:
> Update gpio.txt based on recent discussions regarding interaction with the
> pinctrl subsystem.
> Previously, gpio_request() was described as explicitly not performing any
> required mux setup operations etc.
> Now, gpio_request() is explicitly as explicitly performing any required mux
> setup operations where possible. In the case it isn't, platform code is
> required to have set up any required muxing or other configuration prior to
> gpio_request() being called, in order to maintain the same semantics.

So what if you need to have the pin as a GPIO, manipulate it as a GPIO,
and then hand it off to a special function, and then take it back as
a GPIO before you shut the special function down ?

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