Re: [PATCH v1 3/4] dt-bindings: media: add wiring property to video-interfaces

[Sam Ravnborg <sam@ravnborg.org>]

Hi Rob.

On Tue, Apr 14, 2020 at 02:40:54PM -0500, Rob Herring wrote:
> On Sun, Apr 12, 2020 at 08:20:11PM +0200, Sam Ravnborg wrote:
> > The wiring property is used to describe the wiring between
> > the connector and the panel. The property can be used when the
> > wiring is used to change the mode from for example
> > BGR to RGB. The first users are the at91sam9 family where
> > such a wiring trick is sometimes used.
> > The possilbe values are so far limited to what is required
> > by the at91sam9 family, but using "text" allows us to extend
> > this in the future.
> > 
> > There exists similar properties today:
> >  - display/tilcdc/tilcdc.txt: blue-and-red-wiring
> >  - display/atmel,lcdc.txt: atmel,lcd-wiring-mode
> > 
> > Neither of the above are defined as endpoint properties.
> > 
> > The new property "wiring" has a more general name and
> > is defined as an endpoint property.
> > It will replace atmel,lcd-wiring-mode and may replace
> > blue-and-red-wiring.
> > 
> > Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> > Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Hans Verkuil <hverkuil@xs4all.nl>
> > Cc: linux-media@vger.kernel.org
> > ---
> >  Documentation/devicetree/bindings/media/video-interfaces.txt | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
> > index f884ada0bffc..c3bb87c5c9a9 100644
> > --- a/Documentation/devicetree/bindings/media/video-interfaces.txt
> > +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
> > @@ -141,6 +141,9 @@ Optional endpoint properties
> >  - link-frequencies: Allowed data bus frequencies. For MIPI CSI-2, for
> >    instance, this is the actual frequency of the bus, not bits per clock per
> >    lane value. An array of 64-bit unsigned integers.
> > +- wiring: Wiring of data lines to display.
> > +  "straight" - normal wiring.
> 
> Don't really need a property to express this...
> 
> > +  "red-blue-reversed" - red and blue lines reversed.
> 
> For a common property, I think this needs to be looked at in terms of 
> formats and some of the format negotiation work Boris was doing.

OK, I will bite the bullet and try to understand this good enough
to come up with a proposal.
I will delay the conversion a bit, but we are in no hurry.

	Sam