linux-kernel - Re: [PATCH v2 1/2] dt-bindings: drm/bridge: anx7625: MIPI to DP transmitter binding

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Message-ID: <3c6067de-9f3c-b93c-f263-fa5dd09c3270@samsung.com>
Date:   Fri, 11 Oct 2019 13:21:43 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Xin Ji <xji@...logixsemi.com>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Nicolas Boichat <drinkcat@...omium.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Sheng Pan <span@...logixsemi.com>
Subject: Re: [PATCH v2 1/2] dt-bindings: drm/bridge: anx7625: MIPI to DP
 transmitter binding

On 11.10.2019 04:21, Xin Ji wrote:
> The ANX7625 is an ultra-low power 4K Mobile HD Transmitter designed
> for portable device. It converts MIPI to DisplayPort 1.3 4K.
>
> You can add support to your board with binding.
>
> Example:
> 	anx7625_bridge: encoder@58 {
> 		compatible = "analogix,anx7625";
> 		reg = <0x58>;
> 		status = "okay";
> 		panel-flags = <1>;
> 		enable-gpios = <&pio 45 GPIO_ACTIVE_HIGH>;
> 		reset-gpios = <&pio 73 GPIO_ACTIVE_HIGH>;
> 		#address-cells = <1>;
> 		#size-cells = <0>;
>
> 		port@0 {
> 		  reg = <0>;
> 		  anx_1_in: endpoint {
> 		    remote-endpoint = <&mipi_dsi>;
> 		  };
> 		};
>
> 		port@3 {
> 		  reg = <3>;
> 		  anx_1_out: endpoint {
> 		    remote-endpoint = <&panel_in>;
> 		  };
> 		};
> 	};
>
> Signed-off-by: Xin Ji <xji@...logixsemi.com>
> ---
>  .../bindings/display/bridge/anx7625.yaml           | 96 ++++++++++++++++++++++
>  1 file changed, 96 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/anx7625.yaml
>
> diff --git a/Documentation/devicetree/bindings/display/bridge/anx7625.yaml b/Documentation/devicetree/bindings/display/bridge/anx7625.yaml
> new file mode 100644
> index 0000000..fc84683
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/bridge/anx7625.yaml
> @@ -0,0 +1,96 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2019 Analogix Semiconductor, Inc.
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/display/bridge/anx7625.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: Analogix ANX7625 SlimPort (4K Mobile HD Transmitter)
> +
> +maintainers:
> +  - Xin Ji <xji@...logixsemi.com>
> +
> +description: |
> +  The ANX7625 is an ultra-low power 4K Mobile HD Transmitter
> +  designed for portable devices.
> +
> +properties:
> +  "#address-cells": true
> +  "#size-cells": true
> +
> +  compatible:
> +    items:
> +      - const: analogix,anx7625
> +
> +  reg:
> +    maxItems: 1
> +
> +  panel-flags:
> +    description: indicate the panel is internal or external
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  enable-gpios:
> +    description: used for power on chip control, POWER_EN pin D2.
> +    maxItems: 1
> +
> +  reset-gpios:
> +    description: used for reset chip control, RESET_N pin B7.
> +    maxItems: 1
> +
> +  port@0:
> +    type: object
> +    description:
> +      A port node pointing to MIPI DSI host port node.
> +
> +  port@1:
> +    type: object
> +    description:
> +      A port node pointing to MIPI DPI host port node.
> +
> +  port@2:
> +    type: object
> +    description:
> +      A port node pointing to external connector port node.
> +
> +  port@3:
> +    type: object
> +    description:
> +      A port node pointing to eDP port node.


Decrypting available product brief[1], there are following physical lines:

Input:

- MIPI DSI/DPI - video data, are DSI and DPI lines shared?

- I2S - audio data,

- I2C - control line,

- ALERT/INTP - interrupt,

- USB 3.1 SSRc/Tx - for USB forwarding,

Output:

- SS1, SS2,

- SBU/AUX,

- CC1/2.


Having this information I try to understand ports defined by you:

- port@2 you have defined as pointing to external port, but here the
port should be rather subnode of ANX7625 - the chip has CC lines, see
beginning of [2].

- port@3 describes SS1, SS2 and SBU/AUX lines together, am I right? In
USB-C binding SBU and SS lines are represented by different ports,
different approach, but maybe better in this case.


Maybe it would be good to add 2nd example with USB-C port.


[1]:
https://www.analogix.com/system/files/AA-002291-PB-6-ANX7625_ProductBrief.pdf

[2]: Documentation/devicetree/bindings/connector/usb-connector.txt


Regards

Andrzej


> +
> +required:
> +  - "#address-cells"
> +  - "#size-cells"
> +  - compatible
> +  - reg
> +  - port@0
> +  - port@3
> +
> +example:
> +  - |
> +    anx7625_bridge: encoder@58 {
> +        compatible = "analogix,anx7625";
> +        reg = <0x58>;
> +        status = "okay";
> +        panel-flags = <1>;
> +        enable-gpios = <&pio 45 GPIO_ACTIVE_HIGH>;
> +        reset-gpios = <&pio 73 GPIO_ACTIVE_HIGH>;
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        port@0 {
> +          reg = <0>;
> +          anx_1_in: endpoint {
> +            remote-endpoint = <&mipi_dsi>;
> +          };
> +        };
> +
> +        port@3 {
> +          reg = <3>;
> +          anx_1_out: endpoint {
> +            remote-endpoint = <&panel_in>;
> +          };
> +        };
> +    };