linux-kernel - Re: [RFC PATCH] [media]: of: move graph helpers from drivers/media/v4l2-core to drivers/of

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Message-ID: <531AF782.5080801@ti.com>
Date:	Sat, 8 Mar 2014 12:57:06 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Grant Likely <grant.likely@...aro.org>,
	Philipp Zabel <p.zabel@...gutronix.de>
CC:	Sascha Hauer <s.hauer@...gutronix.de>,
	Rob Herring <robherring2@...il.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	Rob Herring <robh+dt@...nel.org>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Philipp Zabel <philipp.zabel@...il.com>
Subject: Re: [RFC PATCH] [media]: of: move graph helpers from drivers/media/v4l2-core
 to drivers/of

On 07/03/14 19:06, Grant Likely wrote:
> On Thu, 27 Feb 2014 10:36:36 +0200, Tomi Valkeinen <tomi.valkeinen@...com> wrote:
>> On 26/02/14 16:48, Philipp Zabel wrote:
>>
>>>> I would like the document to acknowledge the difference from the
>>>> phandle+args pattern used elsewhere and a description of when it would
>>>> be appropriate to use this instead of a simpler binding.
>>>
>>> Alright. The main point of this binding is that the devices may have
>>> multiple distinct ports that each can be connected to other devices.
>>
>> The other main point with this binding are multiple endpoints per port.
>> So you can have, say, a display controller, with single port, which has
>> two endpoints going to two separate LCD panels.
>>
>> In physical level that would usually mean that the same pins from the
>> display controller are connected to two panels. Most likely this would
>> mean that only one panel can be used at a time, possibly with different
>> settings (say, 16 RGB pins for one panel, 24 RGB pins for the other).
> 
> What device is in control in that scenario?

The endpoints in a single port are exclusive, only one can be active at
a time. So the control for the active path would be no different than in
single panel case (for which people have different opinions).

 Tomi



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