Re: [PATCH v3 4/6] dt-bindings: sound: Add support for the Lantiq PEF2256 codec

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 23/03/2023 09:10, Herve Codina wrote:
> On Thu, 23 Mar 2023 08:31:28 +0100
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
> 
>> On 23/03/2023 08:27, Herve Codina wrote:
>>> Hi Krzysztof
>>>
>>> On Wed, 22 Mar 2023 22:59:37 +0100
>>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
>>>   
>>>> On 22/03/2023 14:46, Herve Codina wrote:  
>>>>> The Lantiq PEF2256 is a framer and line interface component designed to
>>>>> fulfill all required interfacing between an analog E1/T1/J1 line and the
>>>>> digital PCM system highway/H.100 bus.
>>>>>
>>>>> The codec support allows to use some of the PCM system highway
>>>>> time-slots as audio channels to transport audio data over the E1/T1/J1
>>>>> lines.
>>>>>
>>>>> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
>>>>> ---
>>>>>  .../bindings/sound/lantiq,pef2256-codec.yaml  | 54 +++++++++++++++++++
>>>>>  1 file changed, 54 insertions(+)
>>>>>  create mode 100644 Documentation/devicetree/bindings/sound/lantiq,pef2256-codec.yaml
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/sound/lantiq,pef2256-codec.yaml b/Documentation/devicetree/bindings/sound/lantiq,pef2256-codec.yaml
>>>>> new file mode 100644
>>>>> index 000000000000..da35b70cda99
>>>>> --- /dev/null
>>>>> +++ b/Documentation/devicetree/bindings/sound/lantiq,pef2256-codec.yaml
>>>>> @@ -0,0 +1,54 @@
>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>> +%YAML 1.2
>>>>> +---
>>>>> +$id: http://devicetree.org/schemas/sound/lantiq,pef2256-codec.yaml#
>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>> +
>>>>> +title: Lantiq PEF2256 codec
>>>>> +
>>>>> +maintainers:
>>>>> +  - Herve Codina <herve.codina@bootlin.com>
>>>>> +
>>>>> +description: |
>>>>> +  Codec support for PEF2256.
>>>>> +
>>>>> +  The Lantiq PEF2256, also known as Infineon PEF2256 or FALC56, is a framer and
>>>>> +  line interface component designed to fulfill all required interfacing between
>>>>> +  an analog E1/T1/J1 line and the digital PCM system highway/H.100 bus.
>>>>> +
>>>>> +  The codec support allows to use some of the PCM system highway time-slots as
>>>>> +  audio channels to transport audio data over the E1/T1/J1 lines.
>>>>> +
>>>>> +  The time-slots used by the codec must be set and so, the properties
>>>>> +  'dai-tdm-slot-num', 'dai-tdm-slot-width', 'dai-tdm-slot-tx-mask' and
>>>>> +  'dai-tdm-slot-rx-mask' must be present in the ALSA sound card node for
>>>>> +  sub-nodes that involve the codec. The codec uses 8bit time-slots.
>>>>> +  'dai-tdm-tdm-slot-with' must be set to 8.
>>>>> +  The tx and rx masks define the PEF2256 time-slots assigned to the codec.
>>>>> +
>>>>> +  The PEF2256 codec node should be a child of a PEF2256 node.
>>>>> +  Refer to the bindings described in
>>>>> +  Documentation/devicetree/bindings/mfd/lantiq,pef2256.yaml
>>>>> +
>>>>> +allOf:
>>>>> +  - $ref: dai-common.yaml#
>>>>> +
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    const: lantiq,pef2256-codec
>>>>> +
>>>>> +  '#sound-dai-cells':
>>>>> +    const: 0    
>>>>
>>>> You do not have here any resources, so the entire binding can be dropped
>>>> and merged into the parent.
>>>>
>>>> Best regards,
>>>> Krzysztof
>>>>  
>>>
>>> Ok,
>>> Do you expect all these properties (except compatible) merged at the parent  
>>
>> You have only two properties here - dai cells and name-prefix...
>>
>>> level or may I keep a child node with these properties including the
>>> compatible property (ie. yaml file merge).  
>>
>> I was thinking that these should be merged into parent because usually
>> you do not need child node for this. However now I started to think how
>> the codec driver would look like. Essentially the parent MFD driver
>> would need to register dais...
>>
> 
> There is also something specific to audio, the slots definition
> 'dai-tdm-slot-tx-mask' and 'dai-tdm-slot-rx-mask'. These slots definitions
> are set at the ALSA sound card sub-nodes.
> So, I can have multiple codec in the PEF2256.
> 
> For instance:
>   framer {
>     compatible = "lantiq,pef2256", "simple-mfd";
>     ...
>     pef2256_codec0: codec0 {
>       compatible = "lantiq,pef2256-codec";
>       #sound-dai-cells = <0>;
>     };
>     pef2256_codec1: codec1 {
>       compatible = "lantiq,pef2256-codec";
>       #sound-dai-cells = <0>;
>     };
>   };

Then include it in the example. It would cut short this discussion.


Best regards,
Krzysztof