linux-kernel - Re: [PATCH 1/3] dt-bindings: soc: samsung: exynos-speedy: Document SPEEDY host controller bindings

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Message-ID: <7753293a-0ab1-48b1-abcd-a9cd544cc356@gmail.com>
Date: Fri, 13 Dec 2024 11:47:33 +0200
From: Markuss Broks <markuss.broks@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>
Cc: linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Ivaylo Ivanov <ivo.ivanov.ivanov1@...il.com>,
 Maksym Holovach <nergzd@...gzd723.xyz>
Subject: Re: [PATCH 1/3] dt-bindings: soc: samsung: exynos-speedy: Document
 SPEEDY host controller bindings

Hi Krzysztof,

On 12/13/24 9:40 AM, Krzysztof Kozlowski wrote:
> On 12/12/2024 22:09, Markuss Broks wrote:
>> Add the schema for the Samsung SPEEDY serial bus host controller.
>> The bus has 4 bit wide addresses for addressing devices
>> and 8 bit wide register addressing. Each register is also 8
>> bit long, so the address can be 0-f (hexadecimal), node name
>> for child device follows the format: node_name@[0-f].
>
> This wasn't tested so limited review.
>
> A nit, subject: drop second/last, redundant "bindings". The
> "dt-bindings" prefix is already stating that these are bindings.
> See also:
> https://elixir.bootlin.com/linux/v6.7-rc8/source/Documentation/devicetree/bindings/submitting-patches.rst#L18
>
>> Co-developed-by: Maksym Holovach <nergzd@...gzd723.xyz>
>> Signed-off-by: Maksym Holovach <nergzd@...gzd723.xyz>
>> Signed-off-by: Markuss Broks <markuss.broks@...il.com>
>> ---
>>   .../bindings/soc/samsung/exynos-speedy.yaml        | 78 ++++++++++++++++++++++
> Filename must match compatible.
>
>>   1 file changed, 78 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/soc/samsung/exynos-speedy.yaml b/Documentation/devicetree/bindings/soc/samsung/exynos-speedy.yaml
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..304b322a74ea70f23d8c072b44b6ca86b7cc807f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/soc/samsung/exynos-speedy.yaml
>> @@ -0,0 +1,78 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/soc/samsung/exynos-speedy.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Samsung Exynos SPEEDY serial bus host controller
> Speedy or SPEEDY?
Technically it's an acronym (Serial Protocol in an EffEctive Digital 
waY), but we could agree on if we use the capitalized or uncapitalised 
version and use it consistently throughout.
>
>> +
>> +maintainers:
>> +  - Markuss Broks <markuss.broks@...il.com>
>> +
>> +description:
>> +  Samsung SPEEDY is a proprietary Samsung serial 1-wire bus.
> 1-wire? But not compatible with w1 (onwire)?
Nope, I suppose this requires more clarification, as explained in the 
previous letter, there are several differences between the protocols, 
looking at the Samsung patent. [1]
>
>> +  It is used on various Samsung Exynos chips. The bus can
>> +  address at most 4 bit (16) devices. The devices on the bus
>> +  have 8 bit long register line, and the registers are also
>> +  8 bit long each. It is typically used for communicating with
>> +  Samsung PMICs (s2mps17, s2mps18, ...) and other Samsung chips,
>> +  such as RF parts.
>> +
>> +properties:
>> +  compatible:
>> +    - items:
>> +        - enum:
>> +            - samsung,exynos9810-speedy
>> +        - const: samsung,exynos-speedy
> Drop last compatible and use only SoC specific.
Makes sense, for some reason I didn't realise it doesn't make much sense.
>
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    - const: pclk
> Drop clock-names, not needed for one entry.
>
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - "#address-cells"
>> +  - "#size-cells"
> You do not have them in the properties, anyway required goes before
> additionalProperties
>
>> +
>> +patternProperties:
>> +  "^[a-z][a-z0-9]*@[0-9a-f]$":
> That's odd regex. Look at other bus bindings.
Okay, I'll look into it.
>
>> +    type: object
>> +    additionalProperties: true
>> +
>> +    properties:
>> +      reg:
>> +        maxItems: 1
> maximum: 15
>
>> +
>> +    required:
>> +      - reg
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    speedy0: speedy@...c0000 {
> Drop unused label.
>
>> +      compatible = "samsung,exynos9810-speedy",
>> +                   "samsung-exynos-speedy";
>> +      reg = <0x141c0000 0x2000>;
>> +      #address-cells = <1>;
>> +      #size-cells = <0>;
>> +
> No resources? No clocks? No interrupts?
Will extend the example.
>
>
>
> Best regards,
> Krzysztof

- Markuss


[1] https://patents.google.com/patent/US9882711B1/en