Re: [PATCH v3 04/10] dt-bindings: display: renesas: lvds: Add renesas, companion property

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sam,

On Tue, May 28, 2019 at 06:37:30PM +0200, Sam Ravnborg wrote:
> On Tue, May 28, 2019 at 05:12:28PM +0300, Laurent Pinchart wrote:
> > Add a new optional renesas,companion property to point to the companion
> > LVDS encoder. This is used to support dual-link operation where the main
> > LVDS encoder splits even-numbered and odd-numbered pixels between the
> > two LVDS encoders.
> > 
> > The new property doesn't control the mode of operation, it only
> > describes the relationship between the master and companion LVDS
> > encoders.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
> > Tested-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > ---
> > Changes since v2:
> > 
> > - Clarify when the companion property is required or not allowed
> > 
> > Changes since v1:
> > 
> > - Fixed typo
> > ---
> >  .../devicetree/bindings/display/bridge/renesas,lvds.txt    | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt b/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt
> > index 900a884ad9f5..2d24bd8cbec5 100644
> > --- a/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt
> > +++ b/Documentation/devicetree/bindings/display/bridge/renesas,lvds.txt
> > @@ -45,6 +45,13 @@ OF graph bindings specified in Documentation/devicetree/bindings/graph.txt.
> >  
> >  Each port shall have a single endpoint.
> >  
> > +Optional properties:
> > +
> > +- renesas,companion : phandle to the companion LVDS encoder. This property is
> > +  mandatory for the first LVDS encoder on D3 and E3 SoCs, and shall point to
> > +  the second encoder to be used as a companion in dual-link mode. It shall not
> > +  be set for any other LVDS encoder.
> 
> If the D3 and E3 socs do not mandate the use of dual-link, then what to
> do in the DT? Because according to the above this property must be
> specified for D3 and E3 SOC's.

This property doesn't enable dual-link mode, it only specifies the
companion LVDS encoder used for dual-link mode, when enabled (through
communication between the LVDS encoder and the LVDS receiver at
runtime).

Jacopo had a similar comment so I suppose this isn't clear. How would
you word it to make it clear ?

> > +
> >  
> >  Example:
> 
> Always good with examples, maybe it comes later.

Good point, I'll fix that.

-- 
Regards,

Laurent Pinchart
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