On Tue, Nov 17, 2015 at 9:35 PM, Rob Herring <robh@xxxxxxxxxx> wrote: > On Tue, Nov 17, 2015 at 11:07:57AM +0100, Markus Pargmann wrote: >> Add a binding for GPIO initialization. > > Some comments, but they are really more on the gpio hog. I must have > missed them. They are already merged, and in use :( >> +Optional properties: >> +- line-name: The GPIO label name. If not present the node name is used. > > We already have "label" for this purpose. I would rather say we already have another instance of "line-name" for this purpose. See Documentation/devicetree/bindings/gpio/gpio.txt "label" was not chosen because it's a Linuxism (that is what the internal API is using) and not to the point. I like the clear "line" specifier over "pin" etc since GPIOs can be chip-internal and what not. >> + The following two options are mutually exclusive. One of them should be >> + specified, but not both: >> +- gpio-hog: A property specifying that this child node represent a GPIO hog. >> +- gpio-initval: This GPIO should be initialized to the specified configuration. >> + >> + The following three options are mutually exclusive. They change the setting of >> + the GPIO pin. One of them should be specified: >> - input: A property specifying to set the GPIO direction as input. >> - output-low A property specifying to set the GPIO direction as output with >> the value low. >> - output-high A property specifying to set the GPIO direction as output with >> the value high. > > If they are mutually exclusive, then it should just be one property with > values. That is much more simple to validate. > > But none of this is really even needed. We can do all this with existing > bindings. Most gpio controllers use 2 cells and the 2nd cell was > reserved for something like this. Simply adding a -gpios property in the > gpio controller node would do the job: > > init-gpios = <&self n (GPIO_ACTIVE_HIGH | GPIO_OUTPUT)>; > hog-gpios = <&self m GPIO_INPUT>; > > Perhaps we don't want to use GPIO_ACTIVE_x here, but we have 31 more > free bits to use. I prefer if the flags to be used for characteristics of the line rather than driving it in any way. Anyway the input/output-low/output-high is already merged, and in use for hogs. We looked at using -gpios in a self-referential manner, but that made it impossible to name the lines, and that is a desired property. Hogged lines need names so we can figure out who is using them during debug etc. It also makes the DT more human-readable. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
