From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH v6 2/8] Documentation: of: Document graph bindings Date: Mon, 10 Mar 2014 12:37:42 +0100 Message-ID: <2406124.RniJY1n1Xd@avalon> References: <1394011242-16783-1-git-send-email-p.zabel@pengutronix.de> <20140307182717.67596C40B43@trevor.secretlab.ca> <1394443690.7380.10.camel@paszta.hi.pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <1394443690.7380.10.camel-+qGW7pzALmz7o/J7KWpOmN53zsg1cpMQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Philipp Zabel Cc: Grant Likely , Mauro Carvalho Chehab , Russell King - ARM Linux , Rob Herring , Sylwester Nawrocki , Guennadi Liakhovetski , Tomi Valkeinen , Kyungmin Park , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Philipp, On Monday 10 March 2014 10:28:10 Philipp Zabel wrote: > Hi Grant, > > Am Freitag, den 07.03.2014, 18:27 +0000 schrieb Grant Likely: > > On Wed, 5 Mar 2014 10:20:36 +0100, Philipp Zabel wrote: > > > The device tree graph bindings as used by V4L2 and documented in > > > Documentation/device-tree/bindings/media/video-interfaces.txt contain > > > generic parts that are not media specific but could be useful for any > > > subsystem with data flow between multiple devices. This document > > > describes the generic bindings. > > > > > > Signed-off-by: Philipp Zabel > > > > See my comments on the previous version. My concerns are the handling of > > the optional 'ports' node and the usage of reverse links. > > would this change address your concern about the reverse links? As the > preexisting video-interfaces.txt bindings mandate the reverse links, I > worry about introducing a second, subtly different binding. It should be > noted somewhere in video-interfaces.txt that the reverse links are > deprecated for the but still supported by the code for backwards > compatibility. I'm very much against removing the reverse links. Without them the graph will become much more complex to parse. You can try to convince me, but for now I'm afraid it's a NACK. > diff --git a/Documentation/devicetree/bindings/graph.txt > b/Documentation/devicetree/bindings/graph.txt index 1a69c07..eb6cae5 100644 > --- a/Documentation/devicetree/bindings/graph.txt > +++ b/Documentation/devicetree/bindings/graph.txt > @@ -87,12 +87,13 @@ device { > Links between endpoints > ----------------------- > > -Each endpoint should contain a 'remote-endpoint' phandle property that > points -to the corresponding endpoint in the port of the remote device. In > turn, the -remote endpoint should contain a 'remote-endpoint' property. If > it has one, -it must not point to another than the local endpoint. Two > endpoints with their -'remote-endpoint' phandles pointing at each other > form a link between the -containing ports. > +Two endpoint nodes form a link between the two ports they are contained in > +if one contains a 'remote-endpoint' phandle property, pointing to the other > +endpoint. The endpoint pointed to should not contain a 'remote-endpoint' > +property itself. Which direction the phandle should point in depends on > the +device type. In general, links should be pointing outwards from > central +devices that provide DMA memory interfaces, such as display > controller, +video capture interface, or serial digital audio interface > cores. > > device-1 { > port { > @@ -104,8 +105,8 @@ device-1 { > > device-2 { > port { > - device_2_input: endpoint { > - remote-endpoint = <&device_1_output>; > + device_2_input: endpoint { }; > + /* no remote-endpoint, this endpoint is pointed at > */ }; > }; > }; -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html