Re: [PATCH v6 1/5] dt-bindings: msm/dp: add bindings of DP/DP-PLL driver for Snapdragon

[Stephen Boyd <swboyd@chromium.org>]

Quoting Tanmay Shah (2020-06-08 20:38:18)
> diff --git a/Documentation/devicetree/bindings/display/msm/dp-sc7180.yaml b/Documentation/devicetree/bindings/display/msm/dp-sc7180.yaml
> new file mode 100644
> index 0000000..5fdb915
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/msm/dp-sc7180.yaml

Typically the file name matches the compatible string. But the
compatible string is just qcom,dp-display. Maybe the compatible string
should be qcom,sc7180-dp? Notice that the SoC number comes first as is
preferred.


> @@ -0,0 +1,142 @@
> +# SPDX-License-Identifier: (GPL-2.0-only  OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/msm/dp-sc7180.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm Display Port Controller.
> +
> +maintainers:
> +  - Chandan Uddaraju <chandanu@codeaurora.org>
> +  - Vara Reddy <varar@codeaurora.org>
> +  - Tanmay Shah <tanmay@codeaurora.org>
> +
> +description: |
> +  Device tree bindings for MSM Display Port which supports DP host controllers
> +  that are compatible with VESA Display Port interface specification.
> +
> +properties:
> +  compatible:
> +    items:
> +      - const: qcom,dp-display
> +
> +  cell-index:
> +    description: Specifies the controller instance.
> +
> +  reg:
> +    items:
> +      - description: DP controller registers
> +
> +  interrupts:
> +    description: The interrupt signal from the DP block.
> +
> +  clocks:
> +    description: List of clock specifiers for clocks needed by the device.
> +    items:
> +      - description: Display Port AUX clock
> +      - description: Display Port Link clock
> +      - description: Link interface clock between DP and PHY
> +      - description: Display Port Pixel clock
> +      - description: Root clock generator for pixel clock
> +
> +  clock-names:
> +    description: |
> +      Device clock names in the same order as mentioned in clocks property.
> +      The required clocks are mentioned below.
> +    items:
> +      - const: core_aux
> +      - const: ctrl_link
> +      - const: ctrl_link_iface
> +      - const: stream_pixel
> +      - const: pixel_rcg

Why not just 'pixel'? And why is the root clk generator important? It
looks like this binding should be using the assigned clock parents
property instead so that it doesn't have to call clk_set_parent()
explicitly.

> +  "#clock-cells":
> +    const: 1
> +
> +  vdda-1p2-supply:
> +    description: phandle to vdda 1.2V regulator node.
> +
> +  vdda-0p9-supply:
> +    description: phandle to vdda 0.9V regulator node.
> +
> +  data-lanes = <0 1>:

Is this correct? We can have = <value> in the property name? Also feels
generic and possibly should come from the phy binding instead of from
the controller binding.

> +    type: object
> +    description: Maximum number of lanes that can be used for Display port.
> +
> +  ports:
> +    description: |
> +       Contains display port controller endpoint subnode.
> +       remote-endpoint: |
> +         For port@0, set to phandle of the connected panel/bridge's
> +         input endpoint. For port@1, set to the DPU interface output.
> +         Documentation/devicetree/bindings/graph.txt and
> +         Documentation/devicetree/bindings/media/video-interfaces.txt.
> +
> +patternProperties:
> +  "^aux-cfg([0-9])-settings$":
> +    type: object
> +    description: |
> +      Specifies the DP AUX configuration [0-9] settings.
> +      The first entry in this array corresponds to the register offset
> +      within DP AUX, while the remaining entries indicate the
> +      programmable values.

I'd prefer this was removed from the binding and hardcoded in the driver
until we can understand what the values are. If they're not
understandable then they most likely don't change and should be done in
the driver.

> +
> +required:
> +  - compatible
> +  - cell-index
> +  - reg
> +  - interrupts
> +  - clocks
> +  - clock-names
> +  - vdda-1p2-supply
> +  - vdda-0p9-supply
> +  - data-lanes
> +  - ports
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/clock/qcom,dispcc-sdm845.h>
> +    #include <dt-bindings/clock/qcom,gcc-sdm845.h>
> +    msm_dp: displayport-controller@ae90000{
> +        compatible = "qcom,dp-display";
> +        cell-index = <0>;
> +        reg = <0 0xae90000 0 0x1400>;
> +        reg-names = "dp_controller";
> +
> +        interrupt-parent = <&display_subsystem>;
> +        interrupts = <12 0>;
> +
> +        clocks = <&dispcc DISP_CC_MDSS_DP_AUX_CLK>,
> +                 <&dispcc DISP_CC_MDSS_DP_LINK_CLK>,
> +                 <&dispcc DISP_CC_MDSS_DP_LINK_INTF_CLK>,
> +                 <&dispcc DISP_CC_MDSS_DP_PIXEL_CLK>,
> +                 <&dispcc DISP_CC_MDSS_DP_PIXEL_CLK_SRC>;
> +        clock-names = "core_aux",
> +                      "ctrl_link",
> +                      "ctrl_link_iface", "stream_pixel",
> +                      "pixel_rcg";
> +        #clock-cells = <1>;
> +
> +        vdda-1p2-supply = <&vreg_l3c_1p2>;
> +        vdda-0p9-supply = <&vreg_l4a_0p8>;
> +
> +        data-lanes = <0 1>;
> +
> +        ports {
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            port@0 {
> +                reg = <0>;
> +                dp_in: endpoint {
> +                    remote-endpoint = <&dpu_intf0_out>;
> +                };
> +            };
> +
> +            port@1 {
> +                reg = <1>;
> +                dp_out: endpoint {
> +                };
> +            };
> +        };
> +    };

I believe there should be a '...' here.
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