Re: [PATCH 19/22] ASoC: dt-bindings: mt8192: Document audio-routing and dai-link subnode

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 04/03/24 15:23, Rob Herring ha scritto:
> On Tue, Feb 27, 2024 at 01:09:36PM +0100, AngeloGioacchino Del Regno wrote:
>> Document the dai-link subnodes and the audio-routing property, allowing
>> to describe machine specific audio hardware and links in device tree.
>>
>> While at it, also deprecate the old properties which were previously
>> used with the driver's partially hardcoded configuration.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> ---
>>   .../sound/mt8192-mt6359-rt1015-rt5682.yaml    | 129 ++++++++++++++++--
>>   1 file changed, 121 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/sound/mt8192-mt6359-rt1015-rt5682.yaml b/Documentation/devicetree/bindings/sound/mt8192-mt6359-rt1015-rt5682.yaml
>> index 7e50f5d65c8f..78e221003750 100644
>> --- a/Documentation/devicetree/bindings/sound/mt8192-mt6359-rt1015-rt5682.yaml
>> +++ b/Documentation/devicetree/bindings/sound/mt8192-mt6359-rt1015-rt5682.yaml
>> @@ -20,6 +20,15 @@ properties:
>>         - mediatek,mt8192_mt6359_rt1015p_rt5682
>>         - mediatek,mt8192_mt6359_rt1015p_rt5682s
>>   
>> +  audio-routing:
>> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> 
> Already defined in sound-card-common.yaml. Add a $ref.
> 

Right. Done for v2.

>> +    description:
>> +      A list of the connections between audio components. Each entry is a
>> +      pair of strings, the first being the connection's sink, the second
>> +      being the connection's source.
>> +      Valid names could be the input or output widgets of audio components,
>> +      power supplies, MicBias of codec and the software switch.
> 
> Generally the names are defined here.
> 

...but those drivers want to support multiple codecs and multiple boards, so
for each board we would maybe have to add (software defined) names in here
which don't always correspond to a HW pin name (but that's not really a problem).

Sure a subset of the names can't change but, on the other hand, some others
can (as in, may be added).

Hence the question:

Is it mandatory to define the names in an enum here, or can that be avoided?
If it is, I can add them no problem.

>> +
>>     mediatek,platform:
>>       $ref: /schemas/types.yaml#/definitions/phandle
>>       description: The phandle of MT8192 ASoC platform.
>> @@ -27,10 +36,12 @@ properties:
>>     mediatek,hdmi-codec:
>>       $ref: /schemas/types.yaml#/definitions/phandle
>>       description: The phandle of HDMI codec.
>> +    deprecated: true
>>   
>>     headset-codec:
>>       type: object
>>       additionalProperties: false
>> +    deprecated: true
>>   
>>       properties:
>>         sound-dai:
>> @@ -41,6 +52,7 @@ properties:
>>     speaker-codecs:
>>       type: object
>>       additionalProperties: false
>> +    deprecated: true
>>   
>>       properties:
>>         sound-dai:
>> @@ -51,13 +63,83 @@ properties:
>>       required:
>>         - sound-dai
>>   
>> +patternProperties:
>> +  ".*-dai-link$":
>> +    type: object
>> +    description:
>> +      Container for dai-link level properties and CODEC sub-nodes.
>> +
>> +    properties:
>> +      link-name:
>> +        description: Indicates dai-link name and PCM stream name
>> +        items:
>> +          enum:
>> +            - I2S0
>> +            - I2S1
>> +            - I2S2
>> +            - I2S3
>> +            - I2S4
>> +            - I2S5
>> +            - I2S6
>> +            - I2S7
>> +            - I2S8
>> +            - I2S9
>> +            - TDM
>> +
>> +      codec:
>> +        description: Holds subnode which indicates codec dai.
>> +        type: object
>> +        additionalProperties: false
>> +        properties:
>> +          sound-dai:
>> +            minItems: 1
>> +            maxItems: 2
>> +        required:
>> +          - sound-dai
>> +
>> +      dai-format:
>> +        description: audio format
>> +        items:
>> +          enum:
>> +            - i2s
>> +            - right_j
>> +            - left_j
>> +            - dsp_a
>> +            - dsp_b
>> +
>> +      mediatek,clk-provider:
>> +        $ref: /schemas/types.yaml#/definitions/string
>> +        description: Indicates dai-link clock master.
>> +        items:
>> +          enum:
>> +            - cpu
>> +            - codec
>> +
>> +    additionalProperties: false
> 
> Move this before properties.
> 

Done for v2.

>> +
>> +    required:
>> +      - link-name
>> +
>>   additionalProperties: false
>>   
>>   required:
>>     - compatible
>>     - mediatek,platform
>> -  - headset-codec
>> -  - speaker-codecs
>> +
>> +allOf:
>> +  # Disallow dai-link-xxx nodes if the legacy properties are specified
> 
> xxx-dai-link?
> 

Oh! Yes, thanks for catching this.

That's what I initially wanted to do, but then I opted for xxx-dai-link and
forgot to update this comment.

Fixed for v2.

>> +  - if:
>> +      patternProperties:
>> +        ".*-dai-link$": false
>> +    then:
>> +      required:
>> +        - headset-codec
>> +        - speaker-codecs
>> +    else:
>> +      properties:
>> +        headset-codec: false
>> +        speaker-codecs: false
>> +        mediatek,hdmi-codec: false
> 
> Allowing both would preserve compatibility. That's not needed? If so,
> say why in the commit msg.
> 

I'm thinking of writing:

"Since describing machine specific audio hardware and links replaces the
now deprecated old logic doing the same in a driver hardcoded fashion,
it is not allowed to have both the old and new properties together."

...but in short - both the old and the new can do exactly the same, but
imo it doesn't make any sense to actually rely on both as:
  1. It's redundant (and one set of them makes the other useless);
  2. I want to avoid confusion (as the other set won't be parsed);
  3. I'm trying to *enforce* consistency as MTK cards have different
     bindings for .. really, no good reason;
  4. I want to see custom stuff disappear completely (and/or as much as
     possible anyway) and use something that is (at least somewhat) common
     between all MTK and non-MTK or anyway as a start at least consistent
     between MTK cards.

In theory, though, speaking of the driver side, there's nothing preventing
you from specifying both audio-routing xxx-dai-link and mediatek,hdmi-codec,
as the drivers' action will be, in short
    if (new_bindings)
      forget_about_old_bindings_use_the_new_ones();
    else
      use_old_hardcoded_stuff(); /* and be sad */


For that, I really don't want to allow both sets of properties - please, please,
tell me that I don't *have to* remove this block :-)

Cheers,
Angelo