Re: [RFC] irqchip: add support for LS1021A external interrupt lines

[Rob Herring]

On Fri, Dec 15, 2017 at 11:55:34PM +0100, Rasmus Villemoes wrote:
> On 2017-12-13 00:28, Rob Herring wrote:
> > On Fri, Dec 08, 2017 at 03:33:00PM +0100, Rasmus Villemoes wrote:
> >>
> >>  .../interrupt-controller/fsl,ls1021a-extirq.txt    |  19 +++
> > 
> > Please split to separate patch.
> 
> Will do.
> 
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/interrupt-controller/fsl,ls1021a-extirq.txt
> >> @@ -0,0 +1,19 @@
> >> +* Freescale LS1021A external IRQs
> >> +
> >> +The LS1021A supports inverting the polarity of six external interrupt lines.
> >> +
> >> +Required properties:
> >> +- compatible: should be "fsl,ls1021a-extirq"
> >> +- interrupt-controller: Identifies the node as an interrupt controller
> >> +- #interrupt-cells: Use the same format as specified by GIC in arm,gic.txt.
> >> +- interrupt-parent: phandle of GIC.
> >> +- syscon: phandle of Supplemental Configuration Unit (scfg).
> > 
> > Can this be a child of that node instead?
> 
> I suppose it could, but I don't think it would make much sense. In any
> case, I did it this way because that seemed to be the way the syscon
> driver is used in lots of other cases, cf. all the occurrences of
> syscon_regmap_lookup_by_phandle() and the corresponding bindings - I
> don't think I've seen any of those cases represent the syscon-using node
> as a child of the syscon node.

I'm sure there are examples because this is a frequent review comment. 
In any case, define the binding by what the h/w looks like, not what the 
kernel *currently* wants.

Rob