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

Rob Herring
2022-07-18T20:21:19Z

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
>
>