Messages in this thread | | | Date | Mon, 25 Nov 2013 15:34:19 +0100 | Subject | Re: [PATCH] pinctrl: samsung: Allow pin value to be initialized using pinfunc. | From | Linus Walleij <> |
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On Wed, Nov 20, 2013 at 1:02 AM, Kyungmin Park <kmpark@infradead.org> wrote: > On Wed, Nov 20, 2013 at 4:16 AM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> I think that last point should be addressed by having a driver that owns >> the GPIO set it to the desired output level, and the implementation of
> Some pins are not connected (NC). At that cases, there's no drivers to > handle it. To reduce power leakage, it sets proper configuration with > values instead of reset values.
This is correspondant to the PIN_CONFIG_OUTPUT from include/linux/pinctrl/pinconf-generic.h
I.e. driving a pin - any pin, even one that cannot do GPIO - high or low as default.
One could argue that if you can drive the pin high/low using software then by definition it *is* GPIO. Even if it cannot trigger IRQs or anything.
The rationale for having it in pinconf-generic is basically for use cases such that one of the the pin config states the device pass through may relate to what the documentation calls the "GPIO mode fallacy" - a state on the pins that is definately related to the use case of a certain device, but puts the pin in something the manual calls "GPIO mode" in order to save power.
But from a use case point of view that is not GPIO, it is the typically the sleep state of a certain pin when used with a certain device.
I'll see if I can think of some doc patch to make this more clear...
Yours, Linus Walleij
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