On Wed, Jan 14, 2015 at 08:08:09PM +0100, Boris Brezillon wrote: > Hi Jason, > > On Wed, 14 Jan 2015 13:56:19 -0500 > Jason Cooper <jason@xxxxxxxxxxxxxx> wrote: > > > Hey Boris, > > > > On Tue, Jan 13, 2015 at 09:52:07PM +0100, Boris Brezillon wrote: > > > On Tue, 13 Jan 2015 14:00:50 -0500 Jason Cooper <jason@xxxxxxxxxxxxxx> wrote: > > > > On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote: > > > > > Add documentation for the dumb demuxer. > > > > > > > > > > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx> > > > > > --- > > > > > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > > > > > 1 file changed, 34 insertions(+) > > > > > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > new file mode 100644 > > > > > index 0000000..1c777ef > > > > > --- /dev/null > > > > > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > @@ -0,0 +1,34 @@ > > > > > +* Generic Dumb Interrupt Demultiplexer > > > > > + > > > > > +This Dumb demultiplixer simply forward all incoming interrupts to its > > > > > +enabled/unmasked children. > > > > > > > > Please forgive the potentially naïve question, but what hardware is this > > > > describing? > > > > > > That's not a real hardware per se, but on some hardware (like at91 SoCs) > > > some IRQ line are shared by several peripherals, and this dumb > > > demultiplex is here to represent such shared irq lines which cannot be > > > easily demultiplexed (because they do not provide a 'cause' > > > register). > > > > > > You can see it as a virtual irqchip provided to address broken hardware > > > designs. > > > > Hmm. Well, given tglx's recent reply, I suppose I'll *not* go down the > > rabbit hole of "the DT is for describing hardware." :-P > > Actually I'm a bit surprised no one else already mentioned that :-) (I > thought this would be the first complain regarding this dumb irq > demux chip). > > Anyway, IMHO, this can be considered as hardware description since > these irq-lines are really multiplexed into a single one... True, I think the issue is more that the DT node doesn't strictly represent a block of IP. We just need a way to make that clear in the binding doc. > > However, it would probably be a lot more palatable to the DT maintainers > > if we at least change the compatible to prepend "linux,". This way, if > > someone does come up with a better solution down the road, it will be > > much easier to deprecate the binding. > > > > I would also be amenable to "virt,", or "hack,", or even > > "work-around-piss-poor-hw,". Basically, anything that would indicate to > > consumers of the DT that this is not a true reflection of the hardware, > > and that it may be superseded by a better solution later. > > Actually I thought about changing it to "virtual,dumb-irq-demux" :-). Works for me. :) thx, Jason. -- 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
