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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Grant Likely <grant.likely@linaro.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	Mauro Carvalho Chehab <m.chehab@samsung.com>,
	Rob Herring <robh+dt@kernel.org>,
	Sylwester Nawrocki <s.nawrocki@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
	devicetree@vger.kernel.org,
	Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Subject: Re: [PATCH v4 3/3] Documentation: of: Document graph bindings
Date: Sat, 08 Mar 2014 16:43:50 +0100	[thread overview]
Message-ID: <2496453.qPbng50cuV@avalon> (raw)
In-Reply-To: <20140308122532.1AED9C40612@trevor.secretlab.ca>

Hi Grant,

On Saturday 08 March 2014 12:25:32 Grant Likely wrote:
> On Sat, 8 Mar 2014 11:35:38 +0200, Tomi Valkeinen wrote:
> > On 07/03/14 20:11, Grant Likely wrote:
> > >>> 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.
> > 
> > I'm fine with having ports defined in the SoC dtsi. A port is a physical
> > thing, a group of pins, for example.
> > 
> > But an endpoint is a description of the other end of a link. To me, a
> > single endpoint makes no sense, there has to be a pair of endpoints. The
> > board may need 0 to n endpoints, and the SoC dtsi cannot know how many
> > are needed.
> > 
> > If the SoC dtsi defines a single endpoint for a port, and the board
> > needs to use two endpoints for that port, it gets really messy: one
> > endpoint is defined in the SoC dtsi, and used in the board dts. The
> > second endpoint for the same port needs to be defined separately in the
> > board file. I.e. something like:
>
> Sure. If endpoints are logical, then only create the ones actually hooked
> up. No problem there. But nor do I see any issue with having empty
> connections if the board author things it makes sense to have them in the
> dtsi.

I don't mind allowing board authors to add empty connections if they want to, 
but I think it's a good practice not to include them given that endpoint are 
logical. I would at least not include them in the of-graph DT bindings 
examples.

> > /* the first ep */
> > &port1_ep {
> > 	remote-endpoint = <&..>;
> > };
> > 
> > &port1 {
> > 	/* the second ep */
> > 	endpoint@2 {
> > 		remote-endpoint = <&..>;
> > 	};
> > };
> > 
> > Versus:
> > 
> > &port1 {
> > 	/* the first ep */
> > 	endpoint@1 {
> > 		remote-endpoint = <&..>;
> > 	};
> > 	
> > 	/* the second ep */
> > 	endpoint@2 {
> > 		remote-endpoint = <&..>;
> > 	};
> > };

-- 
Regards,

Laurent Pinchart

  reply	other threads:[~2014-03-08 15:43 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-25 14:58 [PATCH v4 0/3] Move device tree graph parsing helpers to drivers/of Philipp Zabel
     [not found] ` < 1393428297.3248.92.camel@paszta.hi.pengutronix.de>
     [not found]   ` <20140307171804. EF245C40A32@trevor.secretlab.ca>
     [not found] ` < 1393340304-19005-2-git-send-email-p.zabel@pengutronix.de>
     [not found]   ` <20140226113729. A9D5AC40A89@trevor.secretlab.ca>
     [not found] ` < 20140226113729.A9D5AC40A89@trevor.secretlab.ca>
     [not found] ` < 1393340304-19005-4-git-send-email-p.zabel@pengutronix.de>
2014-02-25 14:58 ` [PATCH v4 1/3] [media] of: move graph helpers from drivers/media/v4l2-core " Philipp Zabel
2014-02-26 11:37   ` Grant Likely
2014-02-26 15:24     ` Philipp Zabel
2014-03-07 17:18       ` Grant Likely
2014-03-08 10:46         ` Tomi Valkeinen
2014-03-08 12:23           ` Grant Likely
2014-03-08 15:50             ` Laurent Pinchart
2014-03-20 22:23               ` Grant Likely
     [not found]                 ` <20140320222347.CAB6DC412EA-WNowdnHR2B42iJbIjFUEsiwD8/FfD2ys@public.gmane.org>
2014-03-20 22:32                   ` Laurent Pinchart
2014-03-21 13:37                     ` Tomi Valkeinen
2014-03-21 14:10                       ` Sylwester Nawrocki
     [not found]                       ` <532C408D.4070002-l0cyMroinI0@public.gmane.org>
2014-03-21 14:13                         ` Laurent Pinchart
2014-03-21 14:22                           ` Tomi Valkeinen
     [not found]                             ` <532C4B3C.4030406-l0cyMroinI0@public.gmane.org>
2014-03-21 14:30                               ` Laurent Pinchart
2014-03-10  6:34             ` Tomi Valkeinen
2014-03-20 22:26               ` Grant Likely
2014-03-08 12:07         ` Philipp Zabel
     [not found]           ` <CA+gwMcfgKre8S4KHPvTVuAuz672aehGrN1UfFpwKAueTAcrMZQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-03-08 15:54             ` Laurent Pinchart
2014-03-10  6:00               ` Tomi Valkeinen
     [not found]                 ` <531D54E2.8030303-l0cyMroinI0@public.gmane.org>
2014-03-10 13:57                   ` Laurent Pinchart
2014-03-10  8:58               ` Andrzej Hajda
     [not found]                 ` <531D7E9F.3090708-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
2014-03-10  9:29                   ` Tomi Valkeinen
2014-03-10 11:42                   ` Laurent Pinchart
2014-03-11 13:55                     ` Andrzej Hajda
2014-03-20 22:33             ` Grant Likely
2014-02-25 14:58 ` [PATCH v4 2/3] [media] of: move common endpoint parsing " Philipp Zabel
2014-02-25 14:58 ` [PATCH v4 3/3] Documentation: of: Document graph bindings Philipp Zabel
2014-02-26 13:14   ` Tomi Valkeinen
2014-02-26 14:57     ` Philipp Zabel
     [not found]       ` <1393426623.3248.70.camel-+qGW7pzALmz7o/J7KWpOmN53zsg1cpMQ@public.gmane.org>
2014-02-26 14:50         ` Tomi Valkeinen
2014-02-26 15:47           ` Philipp Zabel
     [not found]             ` <1393429676.3248.110.camel-+qGW7pzALmz7o/J7KWpOmN53zsg1cpMQ@public.gmane.org>
2014-02-27  8:08               ` Tomi Valkeinen
2014-02-27 10:52                 ` Philipp Zabel
2014-02-27 10:41                   ` Tomi Valkeinen
     [not found]       ` < 530DFF4C.8080807@ti.com>
     [not found]         ` <530DFF4C.8080807-l0cyMroinI0@public.gmane.org>
2014-03-07 18:11           ` Grant Likely
2014-03-08  9:35             ` Tomi Valkeinen
2014-03-08 12:25               ` Grant Likely
2014-03-08 15:43                 ` Laurent Pinchart [this message]
2014-03-10  6:53                 ` Tomi Valkeinen
     [not found]                   ` <531D6178.3070906-l0cyMroinI0@public.gmane.org>
2014-03-11 13:47                     ` Sylwester Nawrocki
2014-03-07 17:20     ` Grant Likely

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