Re: [RFC PATCH 7/8] dt-bindings: sound: qcom: add Tambora WCD9378 SDCA codec

[Krzysztof Kozlowski <krzk@kernel.org>]

On 23/07/2026 01:42, Srinivas Kandagatla wrote:
> Describe the WCD9378 SDCA peripheral node (compatible sdw20217011000)
> driven by the wcd9378-sdca codec driver for headphone playback, headset
> mic capture and jack detection via the SimpleJack SDCA function type.
> 
> WCD9378 codec can be wired up in 2 different modes.
> "mobile mode" on phone/tablet SoCs is enumerated as tx and rx device,
> each of which has dedicated control and data lines.
> "compute mode" on compute platforms such as Glymur is enumerated as
> single standard MIPI SDCA class device.
> 
> Both modes share same Device ID, compatible; qcom,compute-mode selects
> which driver path is taken.  Supplies, reset GPIO and mic-bias voltages
> live on the SoundWire slave node in compute mode and are forbidden in
> mobile mode (owned by the top-level codec parent there).
> 
> Assisted-by: Claude:claude-opus-4-7
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
> ---
>  .../bindings/sound/qcom,wcd9378-sdw.yaml      | 200 ++++++++++++++++++
>  1 file changed, 200 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/sound/qcom,wcd9378-sdw.yaml
> 
> diff --git a/Documentation/devicetree/bindings/sound/qcom,wcd9378-sdw.yaml b/Documentation/devicetree/bindings/sound/qcom,wcd9378-sdw.yaml
> new file mode 100644
> index 000000000000..2ed4ad92958e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/sound/qcom,wcd9378-sdw.yaml
> @@ -0,0 +1,200 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/sound/qcom,wcd9378-sdw.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm SoundWire Slave devices on WCD9378
> +
> +maintainers:
> +  - Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net>
> +  - Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
> +
> +description: |
> +  The Qualcomm WCD9378 codec presents its SoundWire slave devices with
> +  class ID sdw20217011000 in both operating modes:
> +
> +    * mobile mode -- two slave instances sit on separate SoundWire
> +      masters carrying data only.  A separate top-level codec node
> +      owns the codec's supplies, mic-bias voltages and reset GPIO.
> +
> +    * SDCA / compute mode -- one aggregated slave sits on a multi-lane
> +      master and carries both control and data.  There is no separate
> +      top-level codec node, so the SoundWire slave node itself owns
> +      supplies, reset GPIO and mic-bias voltage configuration.  It is
> +      marked with qcom,compute-mode.
> +
> +  Codec drivers that match sdw20217011000 use qcom,compute-mode to
> +  decide which mode to serve; the presence or absence of this property
> +  also gates whether the supply and mic-bias properties on this node
> +  are required or forbidden.
> +
> +properties:
> +  compatible:
> +    const: sdw20217011000
> +
> +  reg:
> +    maxItems: 1
> +
> +  qcom,compute-mode:
> +    description: |
> +      Marks this SoundWire slave as the single aggregated slave that
> +      implements the codec in SDCA / compute mode.  Only present when
> +      the codec has no separate top-level codec parent; in that case
> +      this slave node also owns the codec's supplies, reset GPIO and
> +      mic-bias voltage configuration.  Absent in mobile mode.

I doubt there is really "compute" or "mobile" mode, so you just wrote to
match use case, but that does not match hardware.

I think there should be no separate top-level codec parent in the first
place, thus this property is not needed. You always list here all resources.

Best regards,
Krzysztof