Re: [PATCH 2/6] dt-bindings: reserved-memory: Support framebuffer reserved memory

[Rob Herring <robh@kernel.org>]

On Mon, Sep 05, 2022 at 06:32:56PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> Document the "framebuffer" compatible string for reserved memory nodes
> to annotate reserved memory regions used for framebuffer carveouts.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  .../bindings/reserved-memory/framebuffer.yaml | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reserved-memory/framebuffer.yaml
> 
> diff --git a/Documentation/devicetree/bindings/reserved-memory/framebuffer.yaml b/Documentation/devicetree/bindings/reserved-memory/framebuffer.yaml
> new file mode 100644
> index 000000000000..80574854025d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reserved-memory/framebuffer.yaml
> @@ -0,0 +1,46 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/reserved-memory/framebuffer.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: /reserved-memory framebuffer node bindings
> +
> +maintainers:
> +  - devicetree-spec@vger.kernel.org
> +
> +allOf:
> +  - $ref: "reserved-memory.yaml"

Don't need quotes.

> +
> +properties:
> +  compatible:
> +    const: framebuffer
> +    description: >
> +      This indicates a region of memory meant to be used as a framebuffer for
> +      a set of display devices. It can be used by an operating system to keep
> +      the framebuffer from being overwritten and use it as the backing memory
> +      for a display device (such as simple-framebuffer).

I'm on the fence whether we need this. It doesn't really add anything 
because 'simple-framebuffer' will reference this node and you can find 
it that way. I guess a bootloader may not setup 'simple-framebuffer', 
but then it should probably not have this node either.

On the flip side, better to have compatibles than not to identify nodes.

> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |

Use '/ {' to skip the boilerplate causing the error.

> +      chosen {
> +        framebuffer {
> +          compatible = "simple-framebuffer";
> +          memory-region = <&fb>;
> +        };
> +      };
> +
> +      reserved-memory {
> +          #address-cells = <1>;
> +          #size-cells = <1>;
> +          ranges;
> +
> +          fb: framebuffer@80000000 {
> +              compatible = "framebuffer";
> +              reg = <0x80000000 0x007e9000>;
> +          };
> +      };
> +
> +...
> -- 
> 2.37.2
> 
>