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From: Grant Likely <grant.likely@linaro.org>
Subject: Re: [PATCH v4 3/3] Documentation: of: Document graph bindings
To: Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Philipp Zabel <p.zabel@pengutronix.de>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
        Mauro Carvalho Chehab <m.chehab@samsung.com>,
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        Kyungmin Park <kyungmin.park@samsung.com>,
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        devicetree@vger.kernel.org,
        Guennadi Liakhovetski <g.liakhovetski@gmx.de>
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Date: Fri, 07 Mar 2014 18:11:32 +0000
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On Wed, 26 Feb 2014 16:50:52 +0200, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> On 26/02/14 16:57, Philipp Zabel wrote:
> > Hi Tomi,
> > 
> > Am Mittwoch, den 26.02.2014, 15:14 +0200 schrieb Tomi Valkeinen:
> >> On 25/02/14 16:58, Philipp Zabel wrote:
> >>
> >>> +Optional endpoint properties
> >>> +----------------------------
> >>> +
> >>> +- remote-endpoint: phandle to an 'endpoint' subnode of a remote device node.
> >>
> >> Why is that optional? What use is an endpoint, if it's not connected to
> >> something?
> > 
> > This allows to include the an empty endpoint template in a SoC dtsi for
> > the convenience of board dts writers. Also, the same property is
> > currently listed as optional in video-interfaces.txt.
> > 
> >   soc.dtsi:
> > 	display-controller {
> > 		port {
> > 			disp0: endpoint { };
> > 		};
> > 	};
> > 
> >   board.dts:
> > 	#include "soc.dtsi"
> > 	&disp0 {
> > 		remote-endpoint = <&panel_input>;
> > 	};
> > 	panel {
> > 		port {
> > 			panel_in: endpoint {
> > 				remote-endpoint = <&disp0>;
> > 			};
> > 		};
> > 	};
> > 
> > Any board not using that port can just leave the endpoint disconnected.
> 
> Hmm I see. I'm against that.
> 
> I think the SoC dtsi should not contain endpoint node, or even port node
> (at least usually). It doesn't know how many endpoints, if any, a
> particular board has. That part should be up to the board dts.

Why? We have established precedence for unused devices still being in
the tree. I really see no issue with it.

g.