pinctrl: clean up pinconfig-generic documentation

Reword the section of pinctrl-bindings.txt that describes generic
properties that pinctrl bindings may use. The aim is to make the text
clearer, and more explicitly call out the responsibility of individual
bindings that use the generic properties to define which of the
properties are used, and how.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt

@@ -127,20 +127,16 @@ whether there is any interaction between the child and intermediate parent
 nodes, is again defined entirely by the binding for the individual pin
 controller device.
 
-== Using generic pinconfig options ==
+== Generic pin configuration node content ==
 
-Generic pinconfig parameters can be used by defining a separate node containing
-the applicable parameters (and optional values), like:
+Many data items that are represented in a pin configuration node are common
+and generic. Pin control bindings should use the properties defined below
+where they are applicable; not all of these properties are relevant or useful
+for all hardware or binding structures. Each individual binding document
+should state which of these generic properties, if any, are used, and the
+structure of the DT nodes that contain these properties.
 
-pcfg_pull_up: pcfg_pull_up {
-	bias-pull-up;
-	drive-strength = <20>;
-};
-
-This node should then be referenced in the appropriate pinctrl node as a phandle
-and parsed in the driver using the pinconf_generic_parse_dt_config function.
-
-Supported configuration parameters are:
+Supported generic properties are:
 
 bias-disable		- disable any pin bias
 bias-high-impedance	- high impedance mode ("third-state", "floating")
@@ -160,7 +156,8 @@ low-power-disable	- disable low power mode
 output-low		- set the pin to output mode with low level
 output-high		- set the pin to output mode with high level
 
-Arguments for parameters:
+Some of the generic properties take arguments. For those that do, the
+arguments are described below.
 
 - bias-pull-up, -down and -pin-default take as optional argument on hardware
   supporting it the pull strength in Ohm. bias-disable will disable the pull.
@@ -170,7 +167,5 @@ Arguments for parameters:
 - input-debounce takes the debounce time in usec as argument
   or 0 to disable debouncing
 
-All parameters not listed here, do not take an argument.
-
 More in-depth documentation on these parameters can be found in
 <include/linux/pinctrl/pinconfig-generic.h>