Message-ID: <20250213-pumice-overcrowd-6c22b0d5d66c@spud>
Date: Thu, 13 Feb 2025 20:34:07 +0000
From: Conor Dooley <conor@...nel.org>
To: Svyatoslav Ryhel <clamor95@...il.com>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Robert Foss <rfoss@...nel.org>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
	Jonas Karlman <jonas@...boo.se>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, dri-devel@...ts.freedesktop.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-bindings: display: bridge: Document Solomon
 SSD2825

On Thu, Feb 13, 2025 at 03:56:04PM +0200, Svyatoslav Ryhel wrote:
> Add bindings for Solomon SSD2825 MIPI master bridge chip that connects an
> application processor with traditional parallel LCD interface and an LCD
> driver with MIPI slave interface. The SSD2825 supports both parallel RGB
> interface and serial SPI interface.
> 
> Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> ---
>  .../display/bridge/solomon,ssd2825.yaml       | 140 ++++++++++++++++++
>  1 file changed, 140 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml b/Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml
> new file mode 100644
> index 000000000000..cd7ff971495c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml
> @@ -0,0 +1,140 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/bridge/solomon,ssd2825.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Solomon SSD2825 RGB to MIPI-DSI bridge
> +
> +maintainers:
> +  - Svyatoslav Ryhel <clamor95@...il.com>
> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +properties:
> +  compatible:
> +    const: solomon,ssd2825
> +
> +  reg:
> +    maxItems: 1
> +
> +  reset-gpios: true
> +
> +  dvdd-supply:
> +    description: Regulator for 1.2V digital power supply.
> +
> +  avdd-supply:
> +    description: Regulator for 1.2V analog power supply.
> +
> +  vddio-supply:
> +    description: Regulator for 1.8V IO power supply.
> +
> +  spi-max-frequency:
> +    maximum: 1000000
> +
> +  spi-cpha: true
> +  spi-cpol: true

Should these be required? Supplies should really be required too, since
the device probably cannot function without them?

> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    const: tx_clk

Drop the _clk, since this cannot be anything else! clock-names isn't
really useful when you have just one, so I'd be inclined to say remove
it entirely...

> +  solomon,hs-zero-delay-ns:
> +    description:
> +      HS zero delay period
> +    default: 133
> +
> +  solomon,hs-prep-delay-ns:
> +    description:
> +      HS prep delay period
> +    default: 40

Do these two have limits? Use maximum/minimum to set them if so.
Cheers,
Conor.

> +
> +  ports:
> +    $ref: /schemas/graph.yaml#/properties/ports
> +
> +    properties:
> +      port@0:
> +        $ref: /schemas/graph.yaml#/$defs/port-base
> +        unevaluatedProperties: false
> +        description:
> +          Video port for RGB input
> +
> +        properties:
> +          endpoint:
> +            $ref: /schemas/graph.yaml#/$defs/endpoint-base
> +            unevaluatedProperties: false
> +
> +            properties:
> +              bus-width:
> +                enum: [ 16, 18, 24 ]
> +
> +      port@1:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description:
> +          Video port for DSI output (panel or connector)
> +
> +    required:
> +      - port@0
> +      - port@1
> +
> +required:
> +  - compatible
> +  - ports
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        dsi@2 {
> +            compatible = "solomon,ssd2825";
> +            reg = <2>;
> +
> +            spi-max-frequency = <1000000>;
> +
> +            spi-cpha;
> +            spi-cpol;
> +
> +            reset-gpios = <&gpio 114 GPIO_ACTIVE_LOW>;
> +
> +            dvdd-supply = <&vdd_1v2>;
> +            avdd-supply = <&vdd_1v2>;
> +            vddio-supply = <&vdd_1v8_io>;
> +
> +            solomon,hs-zero-delay-ns = <300>;
> +            solomon,hs-prep-delay-ns = <65>;
> +
> +            clocks = <&ssd2825_tx_clk>;
> +            clock-names = "tx_clk";
> +
> +            ports {
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                port@0 {
> +                    reg = <0>;
> +
> +                    bridge_input: endpoint {
> +                        remote-endpoint = <&dpi_output>;
> +                        bus-width = <24>;
> +                    };
> +                };
> +
> +                port@1 {
> +                    reg = <1>;
> +
> +                    bridge_output: endpoint {
> +                        remote-endpoint = <&panel_input>;
> +                    };
> +                };
> +            };
> +        };
> +    };
> -- 
> 2.43.0
> 

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