linux-kernel - Re: [RFC PATCH v3 4/6] dt-bindings: clock: meson: document A1 SoC audio clock controller driver

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Date: Mon, 22 Apr 2024 09:43:08 +0200
From: Jerome Brunet <jbrunet@...libre.com>
To: Jan Dakinevich <jan.dakinevich@...utedevices.com>
Cc: Krzysztof Kozlowski <krzk@...nel.org>, Neil Armstrong
 <neil.armstrong@...aro.org>, Jerome Brunet <jbrunet@...libre.com>, Michael
  Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Rob
  Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor  Dooley <conor+dt@...nel.org>, Kevin Hilman <khilman@...libre.com>,
 Martin  Blumenstingl <martin.blumenstingl@...glemail.com>, Philipp Zabel
 <p.zabel@...gutronix.de>, Jiucheng Xu <jiucheng.xu@...ogic.com>,
 linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH v3 4/6] dt-bindings: clock: meson: document A1 SoC
 audio clock controller driver


On Sat 20 Apr 2024 at 17:48, Jan Dakinevich <jan.dakinevich@...utedevices.com> wrote:

> On 4/19/24 17:06, Krzysztof Kozlowski wrote:
>> On 19/04/2024 14:58, Jan Dakinevich wrote:
>>> Add device tree bindings for A1 SoC audio clock and reset controllers.
>>>
>>> Signed-off-by: Jan Dakinevich <jan.dakinevich@...utedevices.com>
>> 
>> This is still RFC, so not ready.
>> 
>> Limited, incomplete review follows. Full review will be provided when
>> the work is ready.
>> 
>> Drop "driver" references, e.g. from subject. Bindings are about hardware.
>> 
>> 
>> ....
>> 
>>> +
>>> +  clocks:
>>> +    maxItems: 26
>>> +    items:
>>> +      - description: input main peripheral bus clock
>>> +      - description: input dds_in
>>> +      - description: input fixed pll div2
>>> +      - description: input fixed pll div3
>>> +      - description: input hifi_pll
>>> +      - description: input oscillator (usually at 24MHz)
>>> +    additionalItems:
>>> +      oneOf:
>>> +        - description: slv_sclk[0-9] - slave bit clocks provided by external components
>>> +        - description: slv_lrclk[0-9]- slave sample clocks provided by external components
>> 
>> What does it mean the clocks are optional? Pins could be not routed?
>
> Yes exactly. Pins could be routed in any combination or could be not
> routed at all. It is determined by schematics and that how external
> codecs are configured.
>
>> It's really rare case that clocks within the SoC are optional, so every
>> such case is questionable.
>> 
>> 
>>> +
>>> +  clock-names:
>>> +    maxItems: 26
>>> +    items:
>>> +      - const: pclk
>>> +      - const: dds_in
>>> +      - const: fclk_div2
>>> +      - const: fclk_div3
>>> +      - const: hifi_pll
>>> +      - const: xtal
>>> +    additionalItems:
>>> +      oneOf:
>>> +        - pattern: "^slv_sclk[0-9]$"
>>> +        - pattern: "^slv_lrclk[0-9]$"
>>> +
>>> +required:
>>> +  - compatible
>>> +  - '#clock-cells'
>>> +  - reg
>>> +  - clocks
>>> +  - clock-names
>>> +
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: amlogic,a1-audio-clkc
>>> +    then:
>>> +      required:
>>> +        - '#reset-cells'
>>> +    else:
>>> +      properties:
>>> +        '#reset-cells': false
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/clock/amlogic,a1-pll-clkc.h>
>>> +    #include <dt-bindings/clock/amlogic,a1-peripherals-clkc.h>
>>> +    #include <dt-bindings/clock/amlogic,a1-audio-clkc.h>
>>> +    audio {
>>> +        #address-cells = <2>;
>>> +        #size-cells = <2>;
>>> +
>>> +        clkc_audio: clock-controller@...50000 {
>>> +                compatible = "amlogic,a1-audio-clkc";
>>> +                reg = <0x0 0xfe050000 0x0 0xb0>;
>>> +                #clock-cells = <1>;
>>> +                #reset-cells = <1>;
>>> +                clocks = <&clkc_audio_vad AUD_CLKID_VAD_AUDIOTOP>,
>>> +                         <&clkc_periphs CLKID_DDS_IN>,
>>> +                         <&clkc_pll CLKID_FCLK_DIV2>,
>>> +                         <&clkc_pll CLKID_FCLK_DIV3>,
>>> +                         <&clkc_pll CLKID_HIFI_PLL>,
>>> +                         <&xtal>;
>>> +                clock-names = "pclk",
>>> +                              "dds_in",
>>> +                              "fclk_div2",
>>> +                              "fclk_div3",
>>> +                              "hifi_pll",
>>> +                              "xtal";
>> 
>> Make it complete - list all clocks.
>> 
>
> You mean, all optional clocks should be mentioned here. Right?
>
>>> +        };
>>> +
>>> +        clkc_audio_vad: clock-controller@...54800 {
>> 
>> Just keep one example. It's basically almost the same.
>> 
>
> The worth of this duplication is to show how a clock from second
> controller (<&clkc_audio_vad AUD_CLKID_VAD_AUDIOTOP>) is used by first
> one. May be it would be better to keep it... What do you think?

If you think that is worth mentioning, make it part of the
documentation, not the example.

>
>> 
>> 
>> Best regards,
>> Krzysztof
>> 


-- 
Jerome