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Date: Wed, 18 Apr 2018 09:16:58 +0200
From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Peter Rosin <peda@axentia.se>
Cc: linux-kernel@vger.kernel.org, David Airlie <airlied@linux.ie>,
        Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
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Subject: Re: [PATCH v2 2/6] dt-bindings: display: atmel: optional
 video-interface of endpoints
Message-ID: <20180418091658.690e3d5e@bbrezillon>
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Hi Peter,

On Tue, 17 Apr 2018 15:10:48 +0200
Peter Rosin <peda@axentia.se> wrote:

> With bus-type/bus-width properties in the endpoint nodes, the video-
> interface of the connection can be specified for cases where the
> heuristic fails to select the correct output mode. This can happen
> e.g. if not all RGB pins are routed on the PCB; the driver has no
> way of knowing this, and needs to be told explicitly.
> 
> This is critical for the devices that have the "conflicting output
> formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant
> RGB bits move around depending on the selected output mode. For
> devices that do not have the "conflicting output formats" issue
> (SAMA5D2, SAMA5D4), this is completely irrelevant.
> 
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt b/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt
> index 82f2acb3d374..244b48869eb4 100644
> --- a/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt
> +++ b/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt
> @@ -15,6 +15,14 @@ Required children nodes:
>   to external devices using the OF graph reprensentation (see ../graph.txt).
>   At least one port node is required.
>  
> +Optional properties in grandchild nodes:
> + Any endpoint grandchild node may specify a desired video interface
> + according to ../../media/video-interfaces.txt, specifically
> + - bus-type: must be <0>.
> + - bus-width: recognized values are <12>, <16>, <18> and <24>, and
> +   override any output mode selection hueristic, forcing "rgb444",
> +   "rgb565", "rgb666" and "rgb888" respectively.
> +

Can you add an example or update the existing one to show how this
should be defined?

>  Example:
>  
>  	hlcdc: hlcdc@f0030000 {


Thanks,

Boris