Re: [PATCH v2 2/4] dt-bindings: display: bridge: Repurpose lvds-encoder

From: Rob Herring <robh+dt@kernel.org>
To: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Mark Rutland <mark.rutland@arm.com>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Simon Horman <horms@verge.net.au>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Magnus Damm <magnus.damm@gmail.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Peter Rosin <peda@axentia.se>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"open list:MEDIA DRIVERS FOR RENESAS - FCP" 
	<linux-renesas-soc@vger.kernel.org>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	Biju Das <biju.das@bp.renesas.com>,
	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
	Jacopo Mondi <jacopo+renesas@jmondi.org>
Subject: Re: [PATCH v2 2/4] dt-bindings: display: bridge: Repurpose lvds-encoder
Date: Tue, 5 Nov 2019 11:07:46 -0600	[thread overview]
Message-ID: <CAL_JsqL6Nzr2oBh51PZnQfBUK1ggDcZUrLaSP2GvEycwFAwJZw@mail.gmail.com> (raw)
In-Reply-To: <TY1PR01MB1770F97A73768451B2ED8A22C07E0@TY1PR01MB1770.jpnprd01.prod.outlook.com>

On Tue, Nov 5, 2019 at 3:33 AM Fabrizio Castro
<fabrizio.castro@bp.renesas.com> wrote:
>
> Hello Rob,
>
> Thank you for your feedback!
>
> > From: Rob Herring <robh+dt@kernel.org>
> > Sent: 04 November 2019 21:23
> > Subject: Re: [PATCH v2 2/4] dt-bindings: display: bridge: Repurpose lvds-encoder
> >
> > On Mon, Nov 4, 2019 at 10:58 AM Fabrizio Castro
> > <fabrizio.castro@bp.renesas.com> wrote:
> > >
> > > In an effort to repurpose lvds-encoder.c to also serve the
> > > function of LVDS decoders, we ended up defining a new "generic"
> > > compatible string, therefore adapt the dt-bindings to fit the
> > > new purpose. Also, convert the dt-bindings from .txt to .yaml
> > > while at it.
> >
> > "Also, ... while at it." is a sign for split into 2 patches.
>
> Will split into 2 patches
>
> >
> > > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > >
> > > ---
> > > v1->v2:
> > > * Converted to dt-schema as per Neil's comment
> > > ---
> > >  .../bindings/display/bridge/lvds-codec.yaml        | 117 +++++++++++++++++++++
> > >  .../bindings/display/bridge/lvds-transmitter.txt   |  66 ------------
> > >  2 files changed, 117 insertions(+), 66 deletions(-)
> > >  create mode 100644 Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> > >  delete mode 100644 Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> > b/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> > > new file mode 100644
> > > index 0000000..ff79bc2
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml
> > > @@ -0,0 +1,117 @@
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/display/bridge/lvds-codec.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Trasnparent LVDS encoders and LVDS decoders
> >
> > Typo
>
> Will fix
>
> >
> > > +
> > > +maintainers:
> > > +  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > > +
> > > +description: |
> > > +  This binding supports transparent LVDS encoders and LVDS decoders that don't
> > > +  require any configuration.
> > > +
> > > +  LVDS is a physical layer specification defined in ANSI/TIA/EIA-644-A. Multiple
> > > +  incompatible data link layers have been used over time to transmit image data
> > > +  to LVDS panels. This binding targets devices compatible with the following
> > > +  specifications only.
> > > +
> > > +  [JEIDA] "Digital Interface Standards for Monitor", JEIDA-59-1999, February
> > > +  1999 (Version 1.0), Japan Electronic Industry Development Association (JEIDA)
> > > +  [LDI] "Open LVDS Display Interface", May 1999 (Version 0.95), National
> > > +  Semiconductor
> > > +  [VESA] "VESA Notebook Panel Standard", October 2007 (Version 1.0), Video
> > > +  Electronics Standards Association (VESA)
> > > +
> > > +  Those devices have been marketed under the FPD-Link and FlatLink brand names
> > > +  among others.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    description: |
> > > +      Any encoder or decoder compatible with this generic binding, but with
> > > +      additional properties not listed here, must define its own binding and
> > > +      list a device specific compatible first followed by the generic compatible
> > > +    items:
> > > +      - enum:
> >
> > You can drop 'items' when there's only 1.
>
> Will drop
>
> >
> > > +        - lvds-encoder # for LVDS encoders
> > > +        - lvds-decoder # for LVDS decoders
> > > +
> > > +  ports:
> > > +    type: object
> > > +    description: |
> > > +      This device has two video ports. Their connections are modeled using the
> > > +      OF graph bindings specified in Documentation/devicetree/bindings/graph.txt
> > > +    properties:
> > > +      port@0:
> > > +        type: object
> > > +        description: |
> > > +          With LVDS encoders port 0 is for parallel input
> > > +          With LVDS decoders port 0 is for LVDS input
> > > +
> > > +      port@1:
> > > +        type: object
> > > +        description: |
> > > +          With LVDS encoders port 1 is for LVDS output
> > > +          With LVDS decoders port 1 is for parallel output
> >
> > port@* are required, right?
>
> Yes, port@0 and port@1 are both required, similarly to:
> Documentation/devicetree/bindings/display/st,stm32-dsi.yaml
> therefore I have put "ports" under "required", in a similar fashion.
> What's the right way of specifying this?

Same as any other property:

required:
  - port@0
  - port@1

At the correct level of course.

Rob