Alexandre Courbot [off-list ref] wrote on Wed [2014-Dec-10 19:56:17 +0900]:

On Fri, Dec 5, 2014 at 6:02 AM, Benoit Parrot [off-list ref] wrote:

quoted

Add GPIO hogging documentation to gpio.txt

Signed-off-by: Benoit Parrot <redacted>
---
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.

quoted

+- 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 :)