Re: [PATCH 2/4] ASoC: dt-bindings: qcom: sm8250: Document "pin-switches" and "widgets"

[Rob Herring <robh@kernel.org>]

On Tue, Dec 14, 2021 at 03:20:47PM +0100, Stephan Gerhold wrote:
> 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.

This all makes sense, but how that translates to the DT properties I 
don't have a clue.

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

And that description is equally as bad.

> 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: Stephan Gerhold <stephan@gerhold.net>
> ---
>  .../devicetree/bindings/sound/qcom,sm8250.yaml   | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)

But nothing new here really, so

Acked-by: Rob Herring <robh@kernel.org>