Re: [PATCH v9 02/10] dt-bindings: display: Document Renesas RZ/G3E display subsystem

[Krzysztof Kozlowski]

On Fri, Oct 23, 2026 at 06:47:35PM +0200, Tommaso Merciai wrote:
> The Renesas RZ/G3E (R9A09G047) SoC has two LCD Controllers, LCDC0 and
> LCDC1, each containing a Display Unit (DU). The two DUs are separate
> instances of the same IP, with their own registers, interrupt, clocks,
> reset and VSP, and are therefore described by two device tree nodes.
> 
> The DSI encoder and channel 1 of the LVDS encoder can be fed by either
> DU, the source being selected at runtime. Driving those outputs from
> either DU requires handling both DUs as a single display subsystem.
> 
> Document the renesas,r9a09g047-display-subsystem node that groups the
> two Display Unit instances.
> 
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> ---
> v8->v9:
>  - New patch.
> 
>  .../renesas,r9a09g047-display-subsystem.yaml  | 44 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 45 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/renesas,r9a09g047-display-subsystem.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/renesas,r9a09g047-display-subsystem.yaml b/Documentation/devicetree/bindings/display/renesas,r9a09g047-display-subsystem.yaml
> new file mode 100644
> index 000000000000..e23cc53a1fea
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/renesas,r9a09g047-display-subsystem.yaml
> @@ -0,0 +1,44 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/renesas,r9a09g047-display-subsystem.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Renesas RZ/G3E Display Subsystem
> +
> +maintainers:
> +  - Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> +
> +description:
> +  The Renesas RZ/G3E display subsystem is a virtual device needed to list the

We do not take bindings for virtual devices, because you do not need
them. Instantiate your driver from existing bindings, instead of
creating fake device just for Linux drivers.

> +  Display Unit instances that comprise the graphics subsystem.
> +
> +properties:
> +  compatible:
> +    const: renesas,r9a09g047-display-subsystem
> +
> +  ports:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array

Properties have only one type and ports is already defined as object for
graph.

Why isn't this a graph?

Best regards,
Krzysztof