linux-kernel - Re: [PATCH v4 1/2] dt-bindings: i2c-mux: Add property for settle time

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Date:   Fri, 12 Nov 2021 13:51:21 -0600
From:   Rob Herring <robh@...nel.org>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
Cc:     peda@...ntia.se, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: i2c-mux: Add property for settle time

On Wed, Nov 03, 2021 at 10:18:38AM +0100, Horatiu Vultur wrote:
> Some HW requires some time for the signals to settle after the muxing is
> changed. Allow this time to be specified in device tree.
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-mux.yaml | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> index 24cac36037f5..4c81e56d02f7 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> +++ b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> @@ -19,6 +19,11 @@ description: |+
>    populating the i2c child busses.  If an 'i2c-mux' subnode is present, only
>    subnodes of this will be considered as i2c child busses.
>  
> +  Optional properties may not be supported by all drivers. However, if a driver
> +  wants to support one of the below features, it should adopt these bindings.

What drivers? Bindings are independent. I don't think you need the 
comment, but this should be a separate change with an explanation along 
the lines of what we discussed.

> +
> +select: false
> +
>  properties:
>    $nodename:
>      pattern: '^(i2c-?)?mux'
> @@ -29,6 +34,11 @@ properties:
>    '#size-cells':
>      const: 0
>  
> +  settle-time-us:
> +    default: 0
> +    description:
> +      The time required for the signals to settle.
> +
>  patternProperties:
>    '^i2c@[0-9a-f]+$':
>      $ref: /schemas/i2c/i2c-controller.yaml
> @@ -41,6 +51,10 @@ patternProperties:
>  
>  additionalProperties: true
>  
> +required:
> +  - '#address-cells'
> +  - '#size-cells'
> +

This too is a separate change.

>  examples:
>    - |
>      /*
> -- 
> 2.33.0
> 
>