* Linus Walleij <linus.walleij@xxxxxxxxxx> [161027 00:57]:
> On Tue, Oct 25, 2016 at 6:45 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
>
> I need some DT person to take a look at this binding and ACK it.
>
> > +For pin controller hardware with a large number of identical registers naming
> > +each bit both can be unmaintainable. Further there can be a large number of similar
> > +pinctrl hardware using the same registers for different purposes depending on the
> > +packaging. For cases like this, the pinctrl driver may use pinctrl-pin-array helper
> > +binding using a hardware based index and a number of configuration values:
>
> Maybe we can reword it a bit so that it is clear that this is an
> either-or approach
> for the pin controller, either they use the pins/groups/functions scheme
> or they use this scheme.
Sure, this is just an optional helper.
> > +pincontroller {
> > + ... /* Standard DT properties for the device itself elided */
> > + #pinctrl-cells = <2>;
> > +
> > + state_0_node_a {
> > + pinctrl-pin-array = <
> > + 0 A_DELAY_PS(0) G_DELAY_PS(120)
> > + 4 A_DELAY_PS(0) G_DELAY_PS(360)
> > + ...
> > + >;
> > + };
> > + ...
> > +};
>
> Looks all right to me. Sad to add to the binding mess, but on the other
> hand, in the overall picture this nicely consolidates and structure
> pinctrl-single.
>
> > +The index for pinctrl-pin-array must relate to the hardware for the pinctrl
> > +registers, and must not be a virtual index of pin instances. The reason for
> > +this is to avoid mapping of the index in the dts files and the pin controller
> > +driver as it can change.
>
> OK
>
> > And we want to avoid another case of interrupt
> > +numbering with pinctrl numbering.
>
> Maybe this file is not a good place for making technical arguments,
> more describing what we agreed on, so cut that sentence IMO.
Sure :)
> > +/*
> > + * For pinctrl binding, typically #pinctrl-cells is for the pin controller
> > + * device, so either parent or grandparent. See pinctrl-bindings.txt.
> > + */
> > +static int pinctrl_find_cells_size(const struct device_node *np,
> > + const char *cells_name)
> > +{
> > + int cells_size, error;
> > +
> > + error = of_property_read_u32(np->parent, cells_name, &cells_size);
> > + if (error) {
> > + error = of_property_read_u32(np->parent->parent,
> > + cells_name, &cells_size);
> > + if (error)
> > + return -ENOENT;
> > + }
> > +
> > + return cells_size;
> > +}
>
> Can't we just hardcode this to "#pinctrl-cells" and skip the cells_name
> parameter? We can parametrize it the day we need it instead.
Sure we can do that.
> The rest of the helpers look nice and clean.
OK cool thanks,
Tony
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