From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Cooper Subject: Re: [PATCH v2 2/5] irqchip: Add DT binding doc for dumb demuxer chips Date: Wed, 14 Jan 2015 14:33:32 -0500 Message-ID: <20150114193332.GC24989@titan.lakedaemon.net> References: <1421174781-4340-1-git-send-email-boris.brezillon@free-electrons.com> <1421174781-4340-3-git-send-email-boris.brezillon@free-electrons.com> <20150113190050.GZ24989@titan.lakedaemon.net> <20150113215207.185d92b4@bbrezillon> <20150114185619.GB24989@titan.lakedaemon.net> <20150114200809.0c16baae@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <20150114200809.0c16baae@bbrezillon> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Boris Brezillon Cc: Thomas Gleixner , Nicolas Ferre , Jean-Christophe Plagniol-Villard , Alexandre Belloni , "Rafael J. Wysocki" , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Wed, Jan 14, 2015 at 08:08:09PM +0100, Boris Brezillon wrote: > Hi Jason, >=20 > On Wed, 14 Jan 2015 13:56:19 -0500 > Jason Cooper wrote: >=20 > > Hey Boris, > >=20 > > On Tue, Jan 13, 2015 at 09:52:07PM +0100, Boris Brezillon wrote: > > > On Tue, 13 Jan 2015 14:00:50 -0500 Jason Cooper wrote: > > > > On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote= : > > > > > Add documentation for the dumb demuxer. > > > > >=20 > > > > > Signed-off-by: Boris Brezillon > > > > > --- > > > > > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++= ++++++++++++++++++ > > > > > 1 file changed, 34 insertions(+) > > > > > create mode 100644 Documentation/devicetree/bindings/interru= pt-controller/dumb-demux.txt > > > > >=20 > > > > > diff --git a/Documentation/devicetree/bindings/interrupt-cont= roller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-con= troller/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 interrup= ts to its > > > > > +enabled/unmasked children. > > > >=20 > > > > Please forgive the potentially na=EFve question, but what hardw= are is this > > > > describing? > > >=20 > > > That's not a real hardware per se, but on some hardware (like at9= 1 SoCs) > > > some IRQ line are shared by several peripherals, and this dumb > > > demultiplex is here to represent such shared irq lines which cann= ot be > > > easily demultiplexed (because they do not provide a 'cause' > > > register). > > >=20 > > > You can see it as a virtual irqchip provided to address broken ha= rdware > > > designs. > >=20 > > 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 >=20 > 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). >=20 > 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 mainta= iners > > 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. > >=20 > > I would also be amenable to "virt,", or "hack,", or even > > "work-around-piss-poor-hw,". Basically, anything that would indica= te to > > consumers of the DT that this is not a true reflection of the hardw= are, > > and that it may be superseded by a better solution later. >=20 > 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" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html