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

Krzysztof Kozlowski
2023-03-26T12:21:57Z

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