From mboxrd@z Thu Jan  1 00:00:00 1970
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCHv2 4/8] Doc/DT: Add DT binding documentation for HDMI
 Connector
Date: Wed, 19 Mar 2014 00:43:33 +0100
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To: Philipp Zabel <p.zabel@pengutronix.de>
Cc: devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org, Russell King - ARM Linux <linux@arm.linux.org.uk>, dri-devel@lists.freedesktop.org, Andrzej Hajda <a.hajda@samsung.com>, Tomi Valkeinen <tomi.valkeinen@ti.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Rob Herring <robherring2@gmail.com>, linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
List-Id: devicetree@vger.kernel.org

Hello,

On Tuesday 18 March 2014 09:43:54 Philipp Zabel wrote:
> Am Dienstag, den 18.03.2014, 10:15 +0200 schrieb Tomi Valkeinen:
> > Add DT binding documentation for HDMI Connector.
> > 
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> > Reviewed-by: Archit Taneja <archit@ti.com>
> > ---
> > 
> >  .../devicetree/bindings/video/hdmi-connector.txt   | 28 +++++++++++++++++
> >  1 file changed, 28 insertions(+)
> >  create mode 100644
> >  Documentation/devicetree/bindings/video/hdmi-connector.txt> 
> > diff --git a/Documentation/devicetree/bindings/video/hdmi-connector.txt
> > b/Documentation/devicetree/bindings/video/hdmi-connector.txt new file
> > mode 100644
> > index 000000000000..ccccc19e2573
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/video/hdmi-connector.txt
> > @@ -0,0 +1,28 @@
> > +HDMI Connector
> > +==============
> > +
> > +Required properties:
> > +- compatible: "hdmi-connector"
> > +- type: the HDMI connector type: "a", "b", "c", "d" or "e"
> > +
> > +Optional properties:
> > +- label: a symbolic name for the connector
> > +
> > +Required nodes:
> > +- Video port for HDMI input
> 
> Geert's comment also applies to all other connector types. These can be
> input connectors, too.

We might not need to define all the properties required by input connectors 
now, but we need to make sure that future extensions will be backward-
compatible. I don't see a problem in making the connector DT bindings depend 
on the direction as long as the direction is specified in the DT node, either 
explicitly or implicitly.

An obvious solution would be to have separate "hdmi-input-connector" and 
"hdmi-output-connector" compatible strings but I don't like that, as there's 
no difference in the HDMI connector itself, only in the usage.

We could also add a "direction" property (possibly later, with a default value 
of "output" in that case), or rely on the link direction, but in the latter 
case that would require reaching an agreement in the current link directions 
debate.

-- 
Regards,

Laurent Pinchart