Hi Grant,
On Tuesday 17 September 2013 17:36:32 Grant Likely wrote:
> On Thu, 12 Sep 2013 17:57:00 +0200, Alexander Holler wrote:
> > Am 12.09.2013 17:19, schrieb Stephen Warren:
> > > IRQs, DMA channels, and GPIOs are all different things. Their bindings
> > > are defined independently. While it's good to define new types of
> > > bindings consistently with other bindings, this hasn't always happened,
> > > so you can make zero assumptions about the IRQ bindings by reading the
> > > documentation for any other kind of binding.
> > >
> > > Multiple interrupts are defined as follows:
> > > // Optional; otherwise inherited from parent/grand-parent/...
> > > interrupt-parent = <&gpio6>;
> > > // Must be in a fixed order, unless binding defines that the
> > > // optional interrupt-names property is to be used.
> > > interrupts = <1 IRQF_TRIGGER_HIGH> <2 IRQF_TRIGGER_LOW>;
> > > // Optional; binding for device defines whether it must
> > > // be present
> > > interrupt-names = "foo", "bar";
> > >
> > > If you need multiple interrupts, each with a different parent, you need
> > > to use an interrupt-map property (Google it for a more complete
> > > explanation I guess). Unlike "interrupts", "interrupt-map" has a phandle
> > > in each entry, and hence each entry can refer to a different IRQ
> > > controller. You end up defining a dummy interrupt controller node (which
> > > may be the leaf node with multiple IRQ outputs, which then points at
> > > itself as the interrupt parent), pointing the leaf node's
> > > interrupt-parent at that node, and then having interrupt-map "demux" the
> > > N interrupt outputs to the various interrupt controllers.
> >
> > What a mess. I assume that is the price that bindings don't have to
> > change.
> >
> > Thanks for clarifying that,
> >
> > Alexander Holler
>
> Actually, I think it is solveable but doing so requires a new binding
> for interrupts. I took a shot at implementing it earlier this week and
> I've got working patches that I'll be posting soon. I created a new
> "interrupts-extended" property that uses a phandle+args type of
> binding like this:
>
> intc1: intc@1000 {
> interrupt-controller;
> #interrupt-cells = <1>;
> };
>
> intc2: intc@2000 {
> interrupt-controller;
> #interrupt-cells = <2>;
> };
>
> device@3000 {
> interrupts-extended = <&intc1 5> <&intc2 3 4> <&intc1 6>;
> };
>
> 'interrupts-extended' will be proposed as a directly replacement of the
> 'interrupts' property and it will eliminate the need for an
> interrupt-map property. A node will be allowed to have one or the other,
> but not both.
>
> I'll write up a proper binding document and post for review.
Any progress on this ? I'll need to use multiple interrupts with different
parents in the near future, I can take this over if needed.
I've also been thinking that we could possibly reuse the "interrupts" property
without defining a new "interrupts-extended". When parsing the property the
code would use the current DT bindings if an interrupt-parent is present, and
the new DT bindings if it isn't.
--
Regards,
Laurent Pinchart
--
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
