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Message-ID: <0c0a22ed-2c4b-374c-4f4c-06afd4e8681d@canonical.com>
Date:   Thu, 20 Jan 2022 08:36:03 +0100
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Subject: Re: [PATCH v3 2/4] spi: dt-bindings: samsung: convert to dtschema
Content-Language: en-US
To:     Pratyush Yadav <p.yadav@ti.com>
Cc:     Andi Shyti <andi@etezian.org>, Mark Brown <broonie@kernel.org>,
        Rob Herring <robh+dt@kernel.org>, linux-spi@vger.kernel.org,
        linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Sam Protsenko <semen.protsenko@linaro.org>
References: <20220112100046.68068-1-krzysztof.kozlowski@canonical.com>
 <20220112100046.68068-3-krzysztof.kozlowski@canonical.com>
 <20220119192758.z3lvlkaeyeiqi73a@ti.com>
 <5f912896-0635-fbe7-4fda-f4cb569190d9@canonical.com>
 <20220120070620.wyeosdstbfcsaplt@ti.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
In-Reply-To: <20220120070620.wyeosdstbfcsaplt@ti.com>
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On 20/01/2022 08:06, Pratyush Yadav wrote:
> On 19/01/22 08:49PM, Krzysztof Kozlowski wrote:
>> On 19/01/2022 20:31, Pratyush Yadav wrote:
>>> On 12/01/22 11:00AM, Krzysztof Kozlowski wrote:
>>>> Convert the Samsung SoC (S3C24xx, S3C64xx, S5Pv210, Exynos) SPI
>>>> controller bindings to DT schema format
>>>>
>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
>>>> Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
>>>> ---
>>>>  .../spi/samsung,spi-peripheral-props.yaml     |  35 ++++
>>>>  .../devicetree/bindings/spi/samsung,spi.yaml  | 187 ++++++++++++++++++
>>>>  .../bindings/spi/spi-peripheral-props.yaml    |   1 +
>>>>  .../devicetree/bindings/spi/spi-samsung.txt   | 122 ------------
>>>>  MAINTAINERS                                   |   2 +-
>>>>  5 files changed, 224 insertions(+), 123 deletions(-)
>>>>  create mode 100644 Documentation/devicetree/bindings/spi/samsung,spi-peripheral-props.yaml
>>>>  create mode 100644 Documentation/devicetree/bindings/spi/samsung,spi.yaml
>>>>  delete mode 100644 Documentation/devicetree/bindings/spi/spi-samsung.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/spi/samsung,spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/samsung,spi-peripheral-props.yaml
>>>> new file mode 100644
>>>> index 000000000000..aa5a1f48494b
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/spi/samsung,spi-peripheral-props.yaml
>>>> @@ -0,0 +1,35 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/spi/samsung,spi-peripheral-props.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: Peripheral-specific properties for Samsung S3C/S5P/Exynos SoC SPI controller
>>>> +
>>>> +maintainers:
>>>> +  - Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
>>>> +
>>>> +description:
>>>> +  See spi-peripheral-props.yaml for more info.
>>>> +
>>>> +properties:
>>>> +  controller-data:
>>>> +    type: object
>>>> +    additionalProperties: false
>>>> +
>>>> +    properties:
>>>> +      samsung,spi-feedback-delay:
>>>> +        description: |
>>>> +          The sampling phase shift to be applied on the miso line (to account
>>>> +          for any lag in the miso line). Valid values:
>>>> +           - 0: No phase shift.
>>>> +           - 1: 90 degree phase shift sampling.
>>>> +           - 2: 180 degree phase shift sampling.
>>>> +           - 3: 270 degree phase shift sampling.
>>>> +        $ref: /schemas/types.yaml#/definitions/uint32
>>>> +        enum: [0, 1, 2, 3]
>>>> +
>>>> +    required:
>>>> +      - samsung,spi-feedback-delay
>>>
>>> I am not quite sure if this required would work here. Let's say another 
>>> controller also uses a controller-data node, but it contains a different 
>>> set of properties. Won't this cause an error to be raised for that 
>>> controller since this property is not there?
>>
>> The controller-data is Samsung SPI specific (does not exist in any other
>> binding), so why would controller-data get added to a different controller?
> 
> It does not as of now, but the name is fairly generic and some 
> controller in the future might use it. I do not think it is a good idea 
> to list required properties in X-peripheral-props.yaml in general since 
> all those will be collected by spi-peripheral-props.yaml and so will 
> apply to _all_ controllers that reference it.

Right, but have in mind this is merely a bindings conversion. These were
made like this long time ago.

I think we can drop the "required:" entirely with the commit 3/4 which
makes it optional.


Best regards,
Krzysztof