Re: [PATCH v8 1/4] dt-bindings: display: Document the Xylon LogiCVC display controller

[Rob Herring <robh@kernel.org>]

On Wed, Dec 23, 2020 at 10:29:44PM +0100, Paul Kocialkowski wrote:
> The Xylon LogiCVC is a display controller implemented as programmable
> logic in Xilinx FPGAs.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> Acked-by: Rob Herring <robh@kernel.org>
> ---
>  .../display/xylon,logicvc-display.yaml        | 313 ++++++++++++++++++
>  1 file changed, 313 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/xylon,logicvc-display.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/xylon,logicvc-display.yaml b/Documentation/devicetree/bindings/display/xylon,logicvc-display.yaml
> new file mode 100644
> index 000000000000..aca78334ad2c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/xylon,logicvc-display.yaml
> @@ -0,0 +1,313 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2019 Bootlin
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/display/xylon,logicvc-display.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: Xylon LogiCVC display controller
> +
> +maintainers:
> +  - Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> +
> +description: |
> +  The Xylon LogiCVC is a display controller that supports multiple layers.
> +  It is usually implemented as programmable logic and was optimized for use
> +  with Xilinx Zynq-7000 SoCs and Xilinx FPGAs.
> +
> +  Because the controller is intended for use in a FPGA, most of the
> +  configuration of the controller takes place at logic configuration bitstream
> +  synthesis time. As a result, many of the device-tree bindings are meant to
> +  reflect the synthesis configuration and must not be configured differently.
> +  Matching synthesis parameters are provided when applicable.
> +
> +  Layers are declared in the "layers" sub-node and have dedicated configuration.
> +  In version 3 of the controller, each layer has fixed memory offset and address
> +  starting from the video memory base address for its framebuffer. In version 4,
> +  framebuffers are configured with a direct memory address instead.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - xylon,logicvc-3.02.a-display
> +      - xylon,logicvc-4.01.a-display
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    minItems: 1
> +    maxItems: 4
> +
> +  clock-names:
> +    minItems: 1
> +    maxItems: 4
> +    items:
> +      # vclk is required and must be provided as first item.
> +      - const: vclk
> +      # Other clocks are optional and can be provided in any order.
> +      - enum:
> +          - vclk2
> +          - lvdsclk
> +          - lvdsclkn
> +      - enum:
> +          - vclk2
> +          - lvdsclk
> +          - lvdsclkn
> +      - enum:
> +          - vclk2
> +          - lvdsclk
> +          - lvdsclkn
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  memory-region:
> +    maxItems: 1
> +
> +  xylon,display-interface:
> +    enum:
> +      # Parallel RGB interface (C_DISPLAY_INTERFACE == 0)
> +      - parallel-rgb
> +      # ITU-T BR656 interface (C_DISPLAY_INTERFACE == 1)
> +      - bt656
> +      # 4-bit LVDS interface (C_DISPLAY_INTERFACE == 2)
> +      - lvds-4bits
> +      # 3-bit LVDS interface (C_DISPLAY_INTERFACE == 4)
> +      - lvds-3bits
> +      # DVI interface (C_DISPLAY_INTERFACE == 5)
> +      - dvi
> +    description: Display output interface (C_DISPLAY_INTERFACE).

As I mentioned before, we have standard properties for these or you know 
the setting based on the panel/bridge attached. 

> +
> +  xylon,display-colorspace:
> +    enum:
> +      # RGB colorspace (C_DISPLAY_COLOR_SPACE == 0)
> +      - rgb
> +      # YUV 4:2:2 colorspace (C_DISPLAY_COLOR_SPACE == 1)
> +      - yuv422
> +      # YUV 4:4:4 colorspace (C_DISPLAY_COLOR_SPACE == 2)
> +      - yuv444
> +    description: Display output colorspace (C_DISPLAY_COLOR_SPACE).
> +
> +  xylon,display-depth:
> +    $ref: "/schemas/types.yaml#/definitions/uint32"
> +    description: Display output depth (C_PIXEL_DATA_WIDTH).
> +
> +  xylon,row-stride:
> +    $ref: "/schemas/types.yaml#/definitions/uint32"
> +    description: Fixed number of pixels in a framebuffer row (C_ROW_STRIDE).
> +
> +  xylon,syscon:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description: |
> +      Syscon phandle representing the top-level logicvc instance, useful when
> +      the parent node is not the top-level logicvc instance.

Why do you need to support both ways? Drop this and require it to be the 
parent node.

> +
> +  xylon,dithering:
> +    $ref: "/schemas/types.yaml#/definitions/flag"
> +    description: Dithering module is enabled (C_XCOLOR)
> +
> +  xylon,background-layer:
> +    $ref: "/schemas/types.yaml#/definitions/flag"
> +    description: |
> +      The last layer is used to display a black background (C_USE_BACKGROUND).
> +      The layer must still be registered.
> +
> +  xylon,layers-configurable:
> +    $ref: "/schemas/types.yaml#/definitions/flag"
> +    description: |
> +      Configuration of layers' size, position and offset is enabled
> +      (C_USE_SIZE_POSITION).
> +
> +  layers:
> +    type: object
> +
> +    properties:
> +      "#address-cells":
> +        const: 1
> +
> +      "#size-cells":
> +        const: 0
> +
> +    patternProperties:
> +      "^layer@[0-9]+$":
> +        type: object
> +
> +        properties:
> +          reg:
> +            maxItems: 1
> +
> +          xylon,layer-depth:
> +            $ref: "/schemas/types.yaml#/definitions/uint32"
> +            description: Layer depth (C_LAYER_X_DATA_WIDTH).
> +
> +          xylon,layer-colorspace:
> +            enum:
> +              # RGB colorspace (C_LAYER_X_TYPE == 0)
> +              - rgb
> +              # YUV packed colorspace (C_LAYER_X_TYPE == 0)
> +              - yuv
> +            description: Layer colorspace (C_LAYER_X_TYPE).
> +
> +          xylon,layer-alpha-mode:
> +            enum:
> +              # Alpha is configured layer-wide (C_LAYER_X_ALPHA_MODE == 0)
> +              - layer
> +              # Alpha is configured per-pixel (C_LAYER_X_ALPHA_MODE == 1)
> +              - pixel
> +            description: Alpha mode for the layer (C_LAYER_X_ALPHA_MODE).
> +
> +          xylon,layer-base-offset:
> +            $ref: "/schemas/types.yaml#/definitions/uint32"
> +            description: |
> +              Offset in number of lines (C_LAYER_X_OFFSET) starting from the
> +              video RAM base (C_VMEM_BASEADDR), only for version 3.
> +
> +          xylon,layer-buffer-offset:
> +            $ref: "/schemas/types.yaml#/definitions/uint32"
> +            description: |
> +              Offset in number of lines (C_BUFFER_*_OFFSET) starting from the
> +              layer base offset for the second buffer used in double-buffering.
> +
> +          xylon,layer-primary:
> +            $ref: "/schemas/types.yaml#/definitions/flag"
> +            description: |
> +              Layer should be registered as a primary plane (exactly one is
> +              required).
> +
> +        additionalProperties: false
> +
> +        required:
> +          - reg
> +          - xylon,layer-depth
> +          - xylon,layer-colorspace
> +          - xylon,layer-alpha-mode
> +
> +    required:
> +      - "#address-cells"
> +      - "#size-cells"
> +      - layer@0
> +
> +    additionalProperties: false
> +
> +    description: |
> +      The description of the display controller layers, containing layer
> +      sub-nodes that each describe a registered layer.
> +
> +  ports:
> +    type: object

You have to define what each port is. If only 1, then use just 'port'.

We now have graph.yaml (in dt-schema). You need to reference that here. 
See drm-misc-next as everything has been converted.

> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +  - interrupts
> +  - xylon,display-interface
> +  - xylon,display-colorspace
> +  - xylon,display-depth
> +  - xylon,row-stride
> +  - layers
> +  - ports
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    logicvc: logicvc@43c00000 {
> +      compatible = "xylon,logicvc-3.02.a", "syscon", "simple-mfd";
> +      reg = <0x43c00000 0x6000>;
> +
> +      #address-cells = <1>;
> +      #size-cells = <1>;
> +
> +      logicvc_display: display@0 {
> +        compatible = "xylon,logicvc-3.02.a-display";
> +        reg = <0x0 0x6000>;
> +
> +        memory-region = <&logicvc_cma>;
> +
> +        clocks = <&logicvc_vclk 0>, <&logicvc_lvdsclk 0>;
> +        clock-names = "vclk", "lvdsclk";
> +
> +        interrupt-parent = <&intc>;
> +        interrupts = <0 34 IRQ_TYPE_LEVEL_HIGH>;
> +
> +        xylon,display-interface = "lvds-4bits";
> +        xylon,display-colorspace = "rgb";
> +        xylon,display-depth = <16>;
> +        xylon,row-stride = <1024>;
> +
> +        xylon,layers-configurable;
> +
> +        layers {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          layer@0 {
> +            reg = <0>;
> +            xylon,layer-depth = <16>;
> +            xylon,layer-colorspace = "rgb";
> +            xylon,layer-alpha-mode = "layer";
> +            xylon,layer-base-offset = <0>;
> +            xylon,layer-buffer-offset = <480>;
> +            xylon,layer-primary;
> +          };
> +
> +          layer@1 {
> +            reg = <1>;
> +            xylon,layer-depth = <16>;
> +            xylon,layer-colorspace = "rgb";
> +            xylon,layer-alpha-mode = "layer";
> +            xylon,layer-base-offset = <2400>;
> +            xylon,layer-buffer-offset = <480>;
> +          };
> +
> +          layer@2 {
> +            reg = <2>;
> +            xylon,layer-depth = <16>;
> +            xylon,layer-colorspace = "rgb";
> +            xylon,layer-alpha-mode = "layer";
> +            xylon,layer-base-offset = <960>;
> +            xylon,layer-buffer-offset = <480>;
> +          };
> +
> +          layer@3 {
> +            reg = <3>;
> +            xylon,layer-depth = <16>;
> +            xylon,layer-colorspace = "rgb";
> +            xylon,layer-alpha-mode = "layer";
> +            xylon,layer-base-offset = <480>;
> +            xylon,layer-buffer-offset = <480>;
> +          };
> +
> +          layer@4 {
> +            reg = <4>;
> +            xylon,layer-depth = <16>;
> +            xylon,layer-colorspace = "rgb";
> +            xylon,layer-alpha-mode = "layer";
> +            xylon,layer-base-offset = <8192>;
> +            xylon,layer-buffer-offset = <480>;
> +          };
> +        };
> +
> +        ports {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          logicvc_out: port@1 {
> +            reg = <1>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            logicvc_output: endpoint@0 {
> +              reg = <0>;
> +              remote-endpoint = <&panel_input>;
> +            };
> +          };
> +        };
> +      };
> +    };
> -- 
> 2.29.2
>