linux-kernel - Re: [PATCH 2/2] dt-bindings: rng: convert Samsung Exynos TRNG to dtschema

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Message-ID: <1960d499-1509-ad42-94d3-f668501fb30b@canonical.com>
Date:   Wed, 18 Aug 2021 08:37:09 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Lukasz Stelmach <l.stelmach@...sung.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH 2/2] dt-bindings: rng: convert Samsung Exynos TRNG to
 dtschema

On 18/08/2021 00:17, Lukasz Stelmach wrote:
> It was <2021-08-17 wto 16:07>, when Krzysztof Kozlowski wrote:
>> On 17/08/2021 14:34, Lukasz Stelmach wrote:
>>> It was <2021-08-17 wto 12:05>, when Krzysztof Kozlowski wrote:
>>>> On 17/08/2021 11:55, Lukasz Stelmach wrote:
>>>>> It was <2021-08-11 śro 10:43>, when Krzysztof Kozlowski wrote:
>>>>>> Convert Samsung Exynos SoC True Random Number Generator bindings to DT
>>>>>> schema format using json-schema.
>>>>>>
>>>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
>>>>>> ---
>>>>>>  .../bindings/rng/samsung,exynos5250-trng.txt  | 17 -------
>>>>>>  .../bindings/rng/samsung,exynos5250-trng.yaml | 44 +++++++++++++++++++
>>>>>>  MAINTAINERS                                   |  2 +-
>>>>>>  3 files changed, 45 insertions(+), 18 deletions(-)
>>>>>>  delete mode 100644 Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
>>>>>>  create mode 100644 Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.yaml
>>>>>>
>>>>>> diff --git
>>>>>> a/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
>>>>>> b/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
>>>>>> deleted file mode 100644
>>>>>> index 5a613a4ec780..000000000000
>>>>>> --- a/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.txt
>>>>>> +++ /dev/null
>>>>>> @@ -1,17 +0,0 @@
>>>>>> -Exynos True Random Number Generator
>>>>>> -
>>>>>> -Required properties:
>>>>>> -
>>>>>> -- compatible  : Should be "samsung,exynos5250-trng".
>>>>>> -- reg         : Specifies base physical address and size of the registers map.
>>>>>> -- clocks      : Phandle to clock-controller plus clock-specifier pair.
>>>>>> -- clock-names : "secss" as a clock name.
>>>>>> -
>>>>>> -Example:
>>>>>> -
>>>>>> -	rng@...30600 {
>>>>>> -		compatible = "samsung,exynos5250-trng";
>>>>>> -		reg = <0x10830600 0x100>;
>>>>>> -		clocks = <&clock CLK_SSS>;
>>>>>> -		clock-names = "secss";
>>>>>> -	};
>>>>>> diff --git
>>>>>> a/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.yaml
>>>>>> b/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.yaml
>>>>>> new file mode 100644
>>>>>> index 000000000000..a50c34d5d199
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.yaml
>>>>>> @@ -0,0 +1,44 @@
>>>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>>>>> +%YAML 1.2
>>>>>> +---
>>>>>> +$id:
>>>>>> https://protect2.fireeye.com/v1/url?k=f38ca35b-ac179a0d-f38d2814-0cc47a31ce52-1faa1ecb65482b8a&q=1&e=8b3490f9-a5fc-4da0-b2ee-7b0aec781403&u=http%3A%2F%2Fdevicetree.org%2Fschemas%2Frng%2Fsamsung%2Cexynos5250-trng.yaml%23
>>>>>> +$schema:
>>>>>> https://protect2.fireeye.com/v1/url?k=9409519d-cb9268cb-9408dad2-0cc47a31ce52-12394c4409905980&q=1&e=8b3490f9-a5fc-4da0-b2ee-7b0aec781403&u=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23
>>>>>> +
>>>>>> +title: Samsung Exynos SoC True Random Number Generator
>>>>>> +
>>>>>> +maintainers:
>>>>>> +  - Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
>>>>>> +  - Łukasz Stelmach <l.stelmach@...sung.com>
>>>>>> +
>>>>>> +properties:
>>>>>> +  compatible:
>>>>>> +    const: samsung,exynos5250-trng
>>>>>> +
>>>>>> +  clocks:
>>>>>> +    maxItems: 1
>>>>>
>>>>> How about copying description from above into the description: property?
>>>>
>>>> But what to copy? There is no description except generic clock bindings.
>>>>
>>>
>>> The description that "was" in the txt file.
>>
>> But there was no description of fields except copy&paste of the core
>> schema. Do you describe C code like:
>>
>> ...
>> /* unsigned int is a integer number greater or equal 0 */
>> unsigned int i;
>> ...
> 
> I believe having descriptions for reg and clocks
> 
>>>>>> -- reg         : Specifies base physical address and size of the registers map.
>>>>>> -- clocks      : Phandle to clock-controller plus clock-specifier pair.
> 
> right next to properties' formal definitions is beneficial for anyone
> browsing the YAML file. If you think otherwise, oh well, I am fine with
> that.

Useful descriptions would be beneficial. Descriptions which are copy of
schema, therefore equal to explaining unsigned int, are not beneficial.
Make the document just unnecessarily bigger, are irrelevant and hide
actual important information. One of the principles is to keep things
simple. Duplicating description from schema into specific bindings is
rather the opposite of such approach.


Best regards,
Krzysztof