Unverified Commit 37a49da9 authored by Stephan Gerhold's avatar Stephan Gerhold Committed by Mark Brown
Browse files

ASoC: dt-bindings: qcom: sm8250: Document "pin-switches" and "widgets" 



Some sound card setups might require extra pin switches to allow
turning off certain audio components. There are two real examples for
this in smartphones/tablets based on MSM8916:

  1. Analog speaker amplifiers connected to headphone outputs.

     The MSM8916 analog codec does not have a separate "Line Out" port
     so some devices have an analog speaker amplifier connected to one
     of the headphone outputs. A pin switch is necessary to allow
     playback on headphones without also activating the speaker.

  2. External speaker codec also used as earpiece.

     Some smartphones have two front-facing (stereo) speakers that can
     be also configured to act as an earpiece during voice calls. A pin
     switch is needed to allow disabling the second speaker during
     voice calls.

There are existing bindings that allow setting up such pin switches in
simple-card.yaml. Document the same for Qcom sound cards.

One variant of example 1 above is added to the examples in the DT
schema: There is an analog speaker amplifier connected to the HPH_R
(right headphone channel) output. Adding a "Speaker" pin switch and
widget allows turning off the speaker when audio should be only played
via the connected headphones.

Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: default avatarStephan Gerhold <stephan@gerhold.net>
Acked-by: default avatarRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211214142049.20422-3-stephan@gerhold.net


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 3d4641a4

Documentation/devicetree/bindings/sound/qcom,sm8250.yaml

+16 −0
Original line number Diff line number Diff line
@@ -39,6 +39,14 @@ properties: 
    $ref: /schemas/types.yaml#/definitions/string

    description: User visible long sound card name



  pin-switches:

    description: List of widget names for which pin switches should be created.

    $ref: /schemas/types.yaml#/definitions/string-array



  widgets:

    description: User specified audio sound widgets.

    $ref: /schemas/types.yaml#/definitions/non-unique-string-array



  # Only valid for some compatibles (see allOf if below)

  reg: true

  reg-names: true
@@ -251,7 +259,15 @@ examples: 
        reg-names = "mic-iomux", "spkr-iomux";



        model = "msm8916";

        widgets =

            "Speaker", "Speaker",

            "Headphone", "Headphones";

        pin-switches = "Speaker";

        audio-routing =

            "Speaker", "Speaker Amp OUT",

            "Speaker Amp IN", "HPH_R",

            "Headphones", "HPH_L",

            "Headphones", "HPH_R",

            "AMIC1", "MIC BIAS Internal1",

            "AMIC2", "MIC BIAS Internal2",

            "AMIC3", "MIC BIAS Internal3";