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Date:   Tue, 4 Apr 2023 10:20:59 -0700
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Subject: Re: [PATCH V4 04/10] dt-bindings: timestamp: Add
 nvidia,gpio-controller
Content-Language: en-US
To:     Thierry Reding <thierry.reding@gmail.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        jonathanh@nvidia.com, linux-kernel@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-gpio@vger.kernel.org,
        linus.walleij@linaro.org, devicetree@vger.kernel.org,
        linux-doc@vger.kernel.org, robh+dt@kernel.org,
        timestamp@lists.linux.dev, krzysztof.kozlowski+dt@linaro.org,
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References: <20230323012929.10815-1-dipenp@nvidia.com>
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 <f523c155-7d05-2034-27ea-e2e56881c0bb@linaro.org>
 <a7539193-8374-cda6-f535-360a4a8eab22@nvidia.com> <ZCv8TviVD8n4MrnW@orome>
From:   Dipen Patel <dipenp@nvidia.com>
In-Reply-To: <ZCv8TviVD8n4MrnW@orome>
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On 4/4/23 3:30 AM, Thierry Reding wrote:
> On Mon, Mar 27, 2023 at 09:58:19AM -0700, Dipen Patel wrote:
>> On 3/25/23 4:07 AM, Krzysztof Kozlowski wrote:
>>> 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@nvidia.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@c1e0000 {
>>>>                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?
>> I have to revert this part back in next patch as when I upgraded dtsschema it gave me errors.
> 
> We need the 0x0 in the DTS files because we have #address-cells = <2>
> and #size-tells = <2>. For the examples, those default to just 1 cell,
> so this can't be an exact copy of what we have in the DTS files.
> 
> Please make sure to always validate the bindings and examples.

Ack...
> 
> Thierry