Re: [PATCH v14 01/10] dt-bindings: mediatek,dp: Add Display Port binding

[Rob Herring <robh@kernel.org>]

On Tue, Jul 12, 2022 at 07:12:14PM +0800, Bo-Chen Chen wrote:
> From: Markus Schneider-Pargmann <msp@baylibre.com>
> 
> This controller is present on several mediatek hardware. Currently
> mt8195 and mt8395 have this controller without a functional difference,
> so only one compatible field is added.
> 
> The controller can have two forms, as a normal display port and as an
> embedded display port.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> ---
>  .../display/mediatek/mediatek,dp.yaml         | 115 ++++++++++++++++++
>  1 file changed, 115 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/mediatek/mediatek,dp.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,dp.yaml b/Documentation/devicetree/bindings/display/mediatek/mediatek,dp.yaml
> new file mode 100644
> index 000000000000..e2d6cb314297
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,dp.yaml
> @@ -0,0 +1,115 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/mediatek/mediatek,dp.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek Display Port Controller
> +
> +maintainers:
> +  - Chun-Kuang Hu <chunkuang.hu@kernel.org>
> +  - Jitao shi <jitao.shi@mediatek.com>
> +
> +description: |
> +  Device tree bindings for the MediaTek display port TX (DP) and
> +  embedded display port TX (eDP) controller present on some MediaTek SoCs.
> +  MediaTek DP and eDP are different hardwares and they have different
> +  base address for registers, so we need two different compatibles to
> +  separate them.

As I said before, 'different base address for registers' is not a reason 
for different compatibles. If it was, then we'd never have a compatible 
string appear more than once in a DT.

Explain WHAT is different within the block. For example[1].

Rob

[1] https://lore.kernel.org/all/20220710084133.30976-10-dmitry.baryshkov@linaro.org/


> +
> +properties:
> +  compatible:
> +    enum:
> +      - mediatek,mt8195-dp-tx
> +      - mediatek,mt8195-edp-tx
> +
> +  reg:
> +    maxItems: 1
> +
> +  nvmem-cells:
> +    maxItems: 1
> +    description: efuse data for display port calibration
> +
> +  nvmem-cell-names:
> +    const: dp_calibration_data
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  ports:
> +    $ref: /schemas/graph.yaml#/properties/ports
> +    properties:
> +      port@0:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: Input endpoint of the controller, usually dp_intf
> +
> +      port@1:
> +        $ref: /schemas/graph.yaml#/$defs/port-base
> +        unevaluatedProperties: false
> +        description: Output endpoint of the controller
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false
> +            properties:
> +              data-lanes:
> +                description: |
> +                  number of lanes supported by the hardware.
> +                  The possible values:
> +                  0       - For 1 lane enabled in IP.
> +                  0 1     - For 2 lanes enabled in IP.
> +                  0 1 2 3 - For 4 lanes enabled in IP.
> +                minItems: 1
> +                maxItems: 4
> +            required:
> +              - data-lanes
> +
> +    required:
> +      - port@0
> +      - port@1
> +
> +  max-linkrate-mhz:
> +    enum: [ 1620, 2700, 5400, 8100 ]
> +    description: maximum link rate supported by the hardware.
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - ports
> +  - max-linkrate-mhz
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/power/mt8195-power.h>
> +    dp_tx@1c600000 {
> +        compatible = "mediatek,mt8195-dp-tx";
> +        reg = <0x1c600000 0x8000>;
> +        power-domains = <&spm MT8195_POWER_DOMAIN_DP_TX>;
> +        interrupts = <GIC_SPI 458 IRQ_TYPE_LEVEL_HIGH 0>;
> +        max-linkrate-mhz = <8100>;
> +
> +        ports {
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            port@0 {
> +                reg = <0>;
> +                dptx_in: endpoint {
> +                    remote-endpoint = <&dp_intf0_out>;
> +                };
> +            };
> +            port@1 {
> +                reg = <1>;
> +                dptx_out: endpoint {
> +                    data-lanes = <0 1 2 3>;
> +                };
> +            };
> +        };
> +    };
> -- 
> 2.18.0
> 
>