Re: [PATCH v1 1/4] ASoC: dt-bindings: qcom,q6apm-lpass-dais: Document DAI subnode

[Krzysztof Kozlowski <krzk@kernel.org>]

On 17/03/2026 06:27, Mohammad Rafi Shaik wrote:
> 
> 
> On 3/10/2026 3:25 PM, Krzysztof Kozlowski wrote:
>> On Mon, Mar 09, 2026 at 04:42:57PM +0530, Mohammad Rafi Shaik wrote:
>>> Extend the qcom,q6apm-lpass-dais device tree binding to explicitly
>>> describe Digital Audio Interface (DAI) child nodes.
>>>
>>> Add #address-cells and #size-cells to allow representation of multiple
>>> DAI instances as child nodes, and define a dai@<id> pattern to document
>>> per-DAI properties such as the interface ID and associated clocks.
>>>
>>> Qualcomm platforms like talos integrate third-party audio codecs or use
>>> different external audio paths. These designs often require additional
>>> configuration such as explicit MI2S MCLK settings for audio to work.
>>>
>>> Co-developed-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
>>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
>>> Signed-off-by: Mohammad Rafi Shaik <mohammad.rafi.shaik@oss.qualcomm.com>
>>> ---
>>>   .../bindings/sound/qcom,q6apm-lpass-dais.yaml | 41 ++++++++++++++++++-
>>>   1 file changed, 40 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/sound/qcom,q6apm-lpass-dais.yaml b/Documentation/devicetree/bindings/sound/qcom,q6apm-lpass-dais.yaml
>>> index 2fb95544d..1d770cbcb 100644
>>> --- a/Documentation/devicetree/bindings/sound/qcom,q6apm-lpass-dais.yaml
>>> +++ b/Documentation/devicetree/bindings/sound/qcom,q6apm-lpass-dais.yaml
>>> @@ -21,6 +21,34 @@ properties:
>>>     '#sound-dai-cells':
>>>       const: 1
>>>   
>>> +  '#address-cells':
>>> +    const: 1
>>> +
>>> +  '#size-cells':
>>> +    const: 0
>>> +
>>> +# Digital Audio Interfaces
>>> +patternProperties:
>>> +  '^dai@[0-9]+$':
>>> +    type: object
>>> +    description:
>>> +      Q6DSP Digital Audio Interfaces.
>>> +
>>> +    properties:
>>> +      reg:
>>> +        description:
>>> +          Digital Audio Interface ID
>>> +
>>> +      clocks:
>>> +        minItems: 1
>>> +        maxItems: 3
>>> +
>>> +      clock-names:
>>> +        minItems: 1
>>> +        maxItems: 3
>>
>> No, this is just way too generic. There is no such syntax in the kernel
>> and this should stop you right there. You are not allowed to add your
>> own style.
>>
>> I don't think DAI is here a separate device needing its own resources
>> expressed in DT. This is still part of ADSP so you just described in DT
>> internal routing between two services on ADSP.
>>
> 
> Thanks for reviewing.
> 
> I’d like to clarify that this is not intended to model the DAI as a 
> separate physical device or to describe internal ADSP routing.

If you do not want to represent the physical device, then I don't think
it should be represented at all.

> 
> Requirement is to allow the kernel to send clock‑voting requests to the 
> ADSP. LPASS MCLK routing is not enabled by default on the ADSP, so the 
> kernel must explicitly request the ADSP to enable the relevant LPASS 
> MCLKs, which is a real hardware control requirement.
> 
> These clocks are LPASS‑owned, and driving them via a third‑party codec 
> is not appropriate. The intent of adding clock capabilities at the DAI 
> level is to allow the kernel to associate LPASS clock votes with a 
> specific DAI instance during stream activity.
> 
> While the DAI itself is not a physical device, some DT representation is 
> required to describe per‑DAI LPASS clock requirements.

DT's purpose is not to describe software constructs, thus DT is not the
answer to your requirement of mapping clocks to specific DAI needs.
Every person adding software properties made "some DT representation is
required" claim.

> 
> I’m open to considering alternative representations, but removing this 
> entirely would leave no generic way for the kernel to handle correct 
> LPASS MCLK voting.

I imagine that, since this is software construct, the software knows
which DAI needs which clock. Clocks are strictly defined, thus driver
should handle all this.


Best regards,
Krzysztof