linux-kernel - Re: [PATCH RFC v2 2/6] ASoC: dt-bindings: qcom,sm8250: Add clocks properties for I2S

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Message-ID: <b614913e-7ebf-4abe-9eb5-f41b81d91ad3@kernel.org>
Date: Thu, 9 Oct 2025 15:29:47 +0100
From: Srinivas Kandagatla <srini@...nel.org>
To: Neil Armstrong <neil.armstrong@...aro.org>,
 Srinivas Kandagatla <srini@...nel.org>, Liam Girdwood <lgirdwood@...il.com>,
 Mark Brown <broonie@...nel.org>, Jaroslav Kysela <perex@...ex.cz>,
 Takashi Iwai <tiwai@...e.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-sound@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH RFC v2 2/6] ASoC: dt-bindings: qcom,sm8250: Add clocks
 properties for I2S



On 10/9/25 3:25 PM, Neil Armstrong wrote:
> On 10/9/25 16:06, Srinivas Kandagatla wrote:
>>
>>
>> On 10/9/25 3:03 PM, Neil Armstrong wrote:
>>> On 10/9/25 15:36, Srinivas Kandagatla wrote:
>>>>
>>>>
>>>> On 10/8/25 7:56 PM, Neil Armstrong wrote:
>>>>> In order to describe the block and master clock of each I2S bus, add
>>>>> the first 5 I2S busses clock entries.
>>>>>
>>>>> The names (primary, secondary, tertiarty, quaternary, quinary, senary)
>>>>> uses the LPASS clock naming which were used for a long time on
>>>>> Qualcomm
>>>>> LPASS firmware interfaces.
>>>>>
>>>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>>>>> ---
>>>>>    .../devicetree/bindings/sound/qcom,sm8250.yaml      | 21 ++++++++++
>>>>> +++++++++++
>>>>>    1 file changed, 21 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/sound/qcom,sm8250.yaml
>>>>> b/Documentation/devicetree/bindings/sound/qcom,sm8250.yaml
>>>>> index
>>>>> 8ac91625dce5ccba5c5f31748c36296b12fac1a6..d1420d138b7ed8152aa53769c4d495e1674275e6 100644
>>>>> --- a/Documentation/devicetree/bindings/sound/qcom,sm8250.yaml
>>>>> +++ b/Documentation/devicetree/bindings/sound/qcom,sm8250.yaml
>>>>> @@ -64,6 +64,27 @@ properties:
>>>>>        $ref: /schemas/types.yaml#/definitions/string
>>>>>        description: User visible long sound card name
>>>>>    +  clocks:
>>>>> +    minItems: 2
>>>>> +    maxItems: 12
>>>>> +
>>>>> +  clock-names:
>>>>> +    minItems: 2
>>>>> +    items:
>>>>> +      # mclk is the I2S Master Clock, mi2s the I2S Bit Clock
>>>>> +      - const: primary-mi2s
>>>>> +      - const: primary-mclk
>>>>> +      - const: secondary-mi2s
>>>>> +      - const: secondary-mclk
>>>>> +      - const: tertiary-mi2s
>>>>> +      - const: tertiary-mclk
>>>>> +      - const: quaternary-mi2s
>>>>> +      - const: quaternary-mclk
>>>>> +      - const: quinary-mi2s
>>>>> +      - const: quinary-mclk
>>>>> +      - const: senary-mi2s
>>>>> +      - const: senary-mclk
>>>>> +
>>>>
>>>> I don't this is correct way to handling bitclk and mclks for I2S, these
>>>> are normally handled as part of snd_soc_dai_set_sysclk() transparently
>>>> without need of any device tree description.
>>>>
>>>> Also doing this way is an issue as this is going to break existing
>>>> Elite
>>>> based platforms, and the device description should not change across
>>>> these both audio firmwares.
>>>
>>> This is only for AudioReach platforms, on those platforms the
>>> clocks are registered in DT and are not accessible by the card.
>>>
>> Clocks will be acessable via snd_soc_dai_set_sysclk ->
>> q6prm_set_lpass_clock once set_sysclk support is added to q6apm-lpass
>> i2s dai ops.
>>
>>
>>> Device description is obviously different for the AudioReach platforms.
>>
>> Why should it be different, its same device.
>> We have platforms that use both Elite and Audioreach.
> 
> I'm perfectly aware of that, it's the case for sc7280/qcm6490. And I agree
> the card bindings is the same, but it doesn't mean the DSP elements are the
> same and uses in the same manner.
> 
> So let's forget the bindings and forget those clocks entries, and imagine
> I'll implement those _sys_sysclk calls like for the Elite platforms.
> This means I'll bypass the clock framework by directly setting the PRM
> clocks, this is clearly a layer violation.

You can claim clocks in the dsp layer (q6apm-lpass-dais) instead of
claiming it in machine layer, it does not necessarily have to bypass the
clk framework.

--srini
> 
> Neil
> 
>>
>> --srini
>>>
>>> Neil
>>>
>>>>
>>>> thanks,
>>>> Srini
>>>>
>>>>>    patternProperties:
>>>>>      ".*-dai-link$":
>>>>>        description:
>>>>>
>>>>
>>>
>>
>