linux-kernel - Re: [PATCH V4 04/10] dt-bindings: timestamp: Add nvidia,gpio-controller

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Date:   Sat, 25 Mar 2023 12:07:08 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Dipen Patel <dipenp@...dia.com>, thierry.reding@...il.com,
        jonathanh@...dia.com, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-gpio@...r.kernel.org,
        linus.walleij@...aro.org, devicetree@...r.kernel.org,
        linux-doc@...r.kernel.org, robh+dt@...nel.org,
        timestamp@...ts.linux.dev, krzysztof.kozlowski+dt@...aro.org,
        brgl@...ev.pl, corbet@....net, gregkh@...uxfoundation.org
Subject: Re: [PATCH V4 04/10] dt-bindings: timestamp: Add
 nvidia,gpio-controller

On 23/03/2023 02:29, Dipen Patel wrote:
> Introducing nvidia,gpio-controller property from Tegra234 SoCs onwards.
> This is done to help below case.
> 
> Without this property code would look like:
> if (of_device_is_compatible(dev->of_node, "nvidia,tegra194-gte-aon"))
> 	hte_dev->c = gpiochip_find("tegra194-gpio-aon",
> 				   tegra_get_gpiochip_from_name);
> else if (of_device_is_compatible(dev->of_node, "nvidia,tegra234-gte-aon"))
> 	hte_dev->c = gpiochip_find("tegra234-gpio-aon",
> 				   tegra_get_gpiochip_from_name);
> else
> 	return -ENODEV;
> 
> This means for every future addition of the compatible string, if else
> condition statements have to be expanded.
> 
> With the property:
> gpio_ctrl = of_parse_phandle(dev->of_node, "nvidia,gpio-controller", 0);
> ....
> hte_dev->c = gpiochip_find(gpio_ctrl, tegra_get_gpiochip_from_of_node);
> 
> This simplifies the code significantly. The introdunction of this
> property/binding does not break existing Tegra194 provider driver.
> 
> Signed-off-by: Dipen Patel <dipenp@...dia.com>
> ---
>  .../timestamp/nvidia,tegra194-hte.yaml        | 31 +++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml
> index eafc33e9ae2e..841273a3d8ae 100644
> --- a/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml
> +++ b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml
> @@ -51,6 +51,12 @@ properties:
>        LIC instance has 11 slices and Tegra234 LIC has 17 slices.
>      enum: [3, 11, 17]
>  
> +  nvidia,gpio-controller:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description:
> +      The phandle to AON gpio controller instance. This is required to handle
> +      namespace conversion between GPIO and GTE.
> +
>    '#timestamp-cells':
>      description:
>        This represents number of line id arguments as specified by the
> @@ -65,22 +71,43 @@ required:
>    - interrupts
>    - "#timestamp-cells"
>  
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - nvidia,tegra234-gte-aon
> +    then:
> +      required:
> +        - nvidia,gpio-controller
> +
>  additionalProperties: false
>  
>  examples:
>    - |
>      tegra_hte_aon: timestamp@...0000 {
>                compatible = "nvidia,tegra194-gte-aon";
> -              reg = <0xc1e0000 0x10000>;
> +              reg = <0x0 0xc1e0000 0x0 0x10000>;

This is not really explained in commit msg... are you sure you tested it?


Best regards,
Krzysztof