Re: [PATCH v10 2/4] dt-bindings: msm: dsi: add yaml schemas for DSI bindings

[Stephen Boyd <swboyd@chromium.org>]

Quoting Krishna Manikandan (2021-02-03 22:42:17)
> Add YAML schema for the device tree bindings for DSI
> controller.
> 
> Signed-off-by: Krishna Manikandan <mkrishn@codeaurora.org>
> 
> Changes in v1:
>     - Separate dsi controller bindings to a separate patch (Stephen Boyd)
>     - Merge dsi-common-controller.yaml and dsi-controller-main.yaml to
>       a single file (Stephen Boyd)
>     - Drop supply entries and definitions from properties (Stephen Boyd)
>     - Modify phy-names property for dsi controller (Stephen Boyd)
>     - Remove boolean from description (Stephen Boyd)
>     - Drop pinctrl properties as they are standard entries (Stephen Boyd)
>     - Modify the description for ports property and keep the reference
>       to the generic binding where this is defined (Stephen Boyd)
>     - Add description to clock names (Stephen Boyd)
>     - Correct the indendation (Stephen Boyd)
>     - Drop the label for display dt nodes and correct the node
>       name (Stephen Boyd)
> ---
>  .../bindings/display/msm/dsi-controller-main.yaml  | 233 +++++++++++++++++++
>  .../devicetree/bindings/display/msm/dsi.txt        | 249 ---------------------
>  2 files changed, 233 insertions(+), 249 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/display/msm/dsi-controller-main.yaml
>  delete mode 100644 Documentation/devicetree/bindings/display/msm/dsi.txt
> 
> diff --git a/Documentation/devicetree/bindings/display/msm/dsi-controller-main.yaml b/Documentation/devicetree/bindings/display/msm/dsi-controller-main.yaml
> new file mode 100644
> index 0000000..9177d01
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/msm/dsi-controller-main.yaml
> @@ -0,0 +1,233 @@
> +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/msm/dsi-controller-main.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Description of Qualcomm Display DSI controller dt properties
> +
> +maintainers:
> +  - Krishna Manikandan <mkrishn@codeaurora.org>
> +
> +description: |
> +  Common Device tree bindings for DSI controller.
> +
> +allOf:
> +  - $ref: "../dsi-controller.yaml#"
> +
> +properties:
> +  compatible:
> +    items:
> +      - const: qcom,mdss-dsi-ctrl
> +
> +  reg:
> +    maxItems: 1
> +
> +  reg-names:
> +    const: dsi_ctrl
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 6

Drop maxItems? Or are some clks optional sometimes?

> +    items:
> +      - description: Display byte clock
> +      - description: Display byte interface clock
> +      - description: Display pixel clock
> +      - description: Display escape clock
> +      - description: Display AHB clock
> +      - description: Display AXI clock
> +
> +  clock-names:
> +    items:
> +      - const: byte
> +      - const: byte_intf
> +      - const: pixel
> +      - const: core
> +      - const: iface
> +      - const: bus
> +
> +  phys:
> +    minItems: 1
> +
> +  phy-names:
> +    const: dsi
> +
> +  syscon-sfpb:
> +    description: A phandle to mmss_sfpb syscon node (only for DSIv2).
> +    $ref: "/schemas/types.yaml#/definitions/phandle"
> +
> +  qcom,mdss-mdp-transfer-time-us:
> +    description: |
> +      Specifies the DSI transfer time for command mode
> +      panels in microseconds. Driver uses this number to adjust
> +      the clock rate according to the expected transfer time.
> +      Increasing this value would slow down the mdp processing
> +      and can result in slower performance.
> +      Decreasing this value can speed up the mdp processing,
> +      but this can also impact power consumption.
> +      As a rule this time should not be higher than the time
> +      that would be expected with the processing at the
> +      DSI link rate since anyways this would be the maximum
> +      transfer time that could be achieved.
> +      If ping pong split is enabled, this time should not be higher
> +      than two times the DSI link rate time.
> +      This is an optional property.
> +    default: 14000

Why is this in DT vs. being tweaked from userspace? This was there
before but it isn't used anywhere in an upstream DTS file so please drop
it.

> +
> +  qcom,dual-dsi-mode:
> +    type: boolean
> +    description: |
> +      Indicates if the DSI controller is driving a panel which needs
> +      2 DSI links.

Shouldn't this be apparent from the OF graph indicating two DSI
endpoints?

> +
> +  qcom,master-dsi:
> +    type: boolean
> +    description: |
> +      Indicates if the DSI controller is driving the master link of
> +      the 2-DSI panel.

When is this not the case? This property looks like some sort of
workaround for driver probe ordering. It was there before though so I
guess this is fine.

> +
> +  qcom,sync-dual-dsi:
> +    type: boolean
> +    description: |
> +      Indicates if the DSI controller is driving a 2-DSI panel whose
> +      2 links need receive command simultaneously.

Feels like it should be a property of the panel node?

> +
> +  ports:
> +    type: object
> +    description: |
> +      Contains DSI controller input and output ports as children, each
> +      containing one endpoint subnode as defined in
> +      Documentation/devicetree/bindings/graph.txt and
> +      Documentation/devicetree/bindings/media/video-interfaces.txt.
> +
> +    properties:
> +      port@0:
> +        type: object
> +        description: |
> +          Input endpoints of the controller.
> +
> +        properties:
> +          reg:
> +            const: 0
> +
> +          endpoint:
> +            type: object
> +            properties:
> +              remote-endpoint:
> +                description: |
> +                  For port@0, set to phandle of the connected panel/bridge's
> +                  input endpoint. For port@1, set to the MDP interface output.
> +                  See Documentation/devicetree/bindings/graph.txt for
> +                  device graph info.
> +
> +              data-lanes:
> +                description: |
> +                  This describes how the physical DSI data lanes are mapped
> +                  to the logical lanes on the given platform. The value contained in
> +                  index n describes what physical lane is mapped to the logical lane n
> +                  (DATAn, where n lies between 0 and 3). The clock lane position is fixed
> +                  and can't be changed. Hence, they aren't a part of the DT bindings. See
> +                  Documentation/devicetree/bindings/media/video-interfaces.txt for
> +                  more info on the data-lanes property.
> +
> +                items:
> +                  - const: 0
> +                  - const: 1
> +                  - const: 2
> +                  - const: 3
> +      port@1:
> +        type: object
> +        description: |
> +          Output endpoints of the controller.
> +        properties:
> +          reg:
> +            const: 1
> +
> +          endpoint:
> +            type: object
> +            properties:
> +              remote-endpoint: true
> +              data-lanes:
> +                items:
> +                  - const: 0
> +                  - const: 1
> +                  - const: 2
> +                  - const: 3
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - interrupts
> +  - clocks
> +  - clock-names
> +  - phys
> +  - phy-names
> +  - ports
> +
> +unevaluatedProperties: false
> +
> +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>
> +
> +     soc {
> +       #address-cells = <2>;
> +       #size-cells = <2>;

The soc node can be left out.

> +
> +       mdss@ae00000 {

subsystem?

> +         #address-cells = <2>;
> +         #size-cells = <2>;
> +         reg = <0 0xae00000 0 0x1000>;
> +         interrupt-controller;
> +         #interrupt-cells = <1>;
> +
> +         dsi@ae94000 {
> +           compatible = "qcom,mdss-dsi-ctrl";