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

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Message-ID: <4c5dc916-ea7a-4d73-b509-49f82ff36666@linaro.org>
Date: Thu, 9 Oct 2025 17:30:18 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: 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 16:29, Srinivas Kandagatla wrote:
> 
> 
> 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.

The current q6afe implementation totally bypasses the clock framework:

static int q6afe_set_lpass_clock_v2(struct q6afe_port *port,
				 struct afe_clk_set *cfg)
{
	return q6afe_port_set_param(port, cfg, AFE_PARAM_ID_CLOCK_SET,
				    AFE_MODULE_CLOCK_SET, sizeof(*cfg));
}

I have no time right now to implement all that for q6apm & q6prm in the
way you propose, so I'll probably not send a new version.

Neil

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