Re: [PATCH v9 31/34] ASoC: qcom: qdsp6: Add headphone jack for offload connection status

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

On 10/17/23 15:01, Wesley Cheng wrote:
> The headphone jack framework has a well defined infrastructure for
> notifying userspace entities through input devices.  Expose a jack device
> that carries information about if an offload capable device is connected.
> Applications can further identify specific offloading information through
> other SND kcontrols.

maybe I am mistaken but if you expose a jack, is there not a need to
implement a .set_jack callback in the component driver?

>  static void q6usb_connector_control_init(struct snd_soc_component *component)
>  {
> +	struct q6usb_port_data *data = dev_get_drvdata(component->dev);
>  	int ret;
>  
>  	ret = snd_ctl_add(component->card->snd_card,
> @@ -290,6 +293,11 @@ static void q6usb_connector_control_init(struct snd_soc_component *component)
>  				snd_ctl_new1(&q6usb_offload_dev_ctrl, component));
>  	if (ret < 0)
>  		return;
> +
> +	ret = snd_soc_card_jack_new(component->card, "USB offload",
> +					SND_JACK_HEADSET, &data->hs_jack);
> +	if (ret)
> +		return;

Also if you report a jack then usually there's a difference between
SND_JACK_HEADPHONE and SND_JACK_HEADSET - where the latter case hints at
capture support.

Clearly you don't have capture support for now, so should this be
SND_JACK_HEADPHONE ?

I must say I still don't get how this entire patchset would be used, for
playback userspace *may* use offload but for any sort of voice call then
userspace *shall* rely on the legacy USB card. Is this not a
show-stopper for CRAS or PipeWire?