Re: [Patch v3 2/2] gpio: Document GPIO hogging mechanism

[Benoit Parrot <bparrot@xxxxxx>]

Alexandre Courbot <gnurou@xxxxxxxxx> wrote on Wed [2014-Dec-10 19:56:17 +0900]:
> On Fri, Dec 5, 2014 at 6:02 AM, Benoit Parrot <bparrot@xxxxxx> wrote:
> > Add GPIO hogging documentation to gpio.txt
> >
> > Signed-off-by: Benoit Parrot <bparrot@xxxxxx>
> > ---
> > Changes since v2:
> >  * Updated to the latest hog syntax.
> >
> > Changes since v1:
> >  * Split the devicetree bindings documentation in its own patch.
> >
> >  Documentation/devicetree/bindings/gpio/gpio.txt | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
> > index 3fb8f53..6d88133 100644
> > --- a/Documentation/devicetree/bindings/gpio/gpio.txt
> > +++ b/Documentation/devicetree/bindings/gpio/gpio.txt
> > @@ -103,6 +103,22 @@ Every GPIO controller node must contain both an empty "gpio-controller"
> >  property, and a #gpio-cells integer property, which indicates the number of
> >  cells in a gpio-specifier.
> >
> > +The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
> > +providing automatic GPIO request and configuration as part of the
> > +gpio-controller's driver probe function.
> > +
> > +Each GPIO hog definition is represented as a child node of the GPIO controller.
> > +Required properties:
> > +- gpio-hog:  A property specifying that this child node represent a gpio-hog.
> > +- gpios:     Store the gpio information (id, flags, ...). Shall contain the
> > +            number of cells specified in its parent node (GPIO controller
> > +            node).
> 
> Since this property will only describe one GPIO, why use the plural
> form? Would it not be confusing?

I would tend to agree in this case but based on this original comment from Linus on this thread:

http://marc.info/?l=linux-gpio&m=138917388625221&w=2
where on 08/01/2014 10:37, Linus Walleij wrote:

  > +Each GPIO hog definition is represented as a child node of the GPIO controller.
  > +Required properties:
  > +- gpio: store the gpio informations (id, flags, ...). Shall contain the
  > +  number of cells specified in its parent node (GPIO controller node).

  This property is alway plural "gpios".

As long as everyone agree, I am fine with it.

> 
> > +- direction: A property specifying the direction/value needed. This property
> > +            can take the folowing values: input, output-high, output-low.
> 
> nit: since this property not only describes the direction but also the
> (potential) value, I suggest to rename it to "state".

Since you are the one who suggested "direction" in the first place, as long as you agree with yourself :)
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