linux-kernel - Re: [PATCH 1/2] dt-bindings: display: bridge: Add documentation for LT8912

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Message-ID: <20210209163820.GB3892603@robh.at.kernel.org>
Date:   Tue, 9 Feb 2021 10:38:20 -0600
From:   Rob Herring <robh@...nel.org>
To:     Adrien Grassein <adrien.grassein@...il.com>
Cc:     airlied@...ux.ie, daniel@...ll.ch, a.hajda@...sung.com,
        narmstrong@...libre.com, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...l.net,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: display: bridge: Add documentation for
 LT8912

On Sun, Jan 24, 2021 at 04:08:34PM +0100, Adrien Grassein wrote:
> Lontium LT8912 is a DSI to HDMI bridge.
> 
> Signed-off-by: Adrien Grassein <adrien.grassein@...il.com>
> ---
>  .../display/bridge/lontium,lt8912.yaml        | 92 +++++++++++++++++++
>  MAINTAINERS                                   |  5 +
>  2 files changed, 97 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/lontium,lt8912.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt8912.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt8912.yaml
> new file mode 100644
> index 000000000000..ed1a6ddaab2f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt8912.yaml
> @@ -0,0 +1,92 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/bridge/lontium,lt8912.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Lontium LT8912 MIPI to HDMI Bridge
> +
> +maintainers:
> +  - Adrien Grassein <adrien.grassein@...il.com>
> +
> +description: |
> +  The LT8912 is a bridge device which convert DSI to HDMI
> +
> +properties:
> +  compatible:
> +    enum:
> +      - lontium,lt8912
> +
> +  reg:
> +    maxItems: 1
> +
> +  ddc-i2c-bus:

This belongs in an hdmi-connector node.

> +    maxItems: 1
> +    description: i2c bus used to read EDID of the connected display.
> +
> +  dsi-lanes:
> +    maxItems: 1
> +    description: dsi lanes count interconnected with lt8912.

'data-lanes' in the graph is the standard way to do this.

You'll need video-interfaces.yaml which is pending in the media tree.

> +
> +  reset-gpios:
> +    maxItems: 1
> +    description: GPIO connected to active high RESET pin.
> +
> +  ports:
> +    $ref: /schemas/graph.yaml#/properties/ports
> +
> +    properties:
> +      port@0:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description:
> +          Primary MIPI port-1 for MIPI input

You're going to need a port for the connector.

> +
> +    required:
> +      - port@0
> +
> +required:
> +  - compatible
> +  - ddc-i2c-bus
> +  - dsi-lanes
> +  - reg
> +  - reset-gpios
> +  - ports
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    i2c4 {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      hdmi-bridge@48 {
> +        compatible = "lontium,lt8912";
> +        reg = <0x48>;
> +        reset-gpios = <&max7323 0 GPIO_ACTIVE_LOW>;
> +        dsi-lanes = <4>;
> +        ddc-i2c-bus = <&ddc_i2c_bus>;
> +
> +        ports {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          port@0 {
> +            reg = <0>;
> +
> +            hdmi_out_in: endpoint {
> +              remote-endpoint = <&mipi_dsi_out>;
> +            };
> +          };
> +        };
> +      };
> +    };
> +
> +    ddc_i2c_bus: i2c5 {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +    };
> +
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5aa18cbfb883..01e7e356bfac 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10472,6 +10472,11 @@ S:	Maintained
>  T:	git git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git
>  F:	drivers/hid/hid-lg-g15.c
>  
> +LONTIUM LT8912 MIPI TO HDMI BRIDGE
> +M:	Adrien Grassein <adrien.grassein@...il.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/display/bridge/lontium,lt8912.yaml
> +
>  LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)
>  M:	Sathya Prakash <sathya.prakash@...adcom.com>
>  M:	Sreekanth Reddy <sreekanth.reddy@...adcom.com>
> -- 
> 2.25.1
>