Re: [PATCH v20 33/41] ASoC: usb: Create SOC USB SND jack kcontrol

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

Hi Amadeusz,

On 4/26/2024 6:26 AM, Amadeusz Sławiński wrote:
> On 4/25/2024 11:51 PM, Wesley Cheng wrote:
> > Expose API for creation of a jack control for notifying of available
> > devices that are plugged in/discovered, and that support offloading.  
> > This
> > allows for control names to be standardized across implementations of USB
> > audio offloading.
> >
> > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> > ---
>
> (...)
>
> >   /* SOC USB sound kcontrols */
> > +/**
> > + * snd_soc_usb_setup_offload_jack() - Create USB offloading jack
> > + * @component: USB DPCM backend DAI component
> > + * @jack: jack structure to create
> > + *
> > + * Creates a jack device for notifying userspace of the availability
> > + * of an offload capable device.
> > + *
> > + * Returns 0 on success, negative on error.
> > + *
> > + */
> > +int snd_soc_usb_setup_offload_jack(struct snd_soc_component *component,
> > +                    struct snd_soc_jack *jack)
> > +{
> > +    int ret;
> > +
> > +    ret = snd_soc_card_jack_new(component->card, "USB Offload 
> > Playback Jack",
> > +                    SND_JACK_HEADPHONE, jack);
> > +    if (ret < 0) {
> > +        dev_err(component->card->dev, "Unable to add USB offload 
> > jack\n");
> > +        return ret;
> > +    }
> > +
> > +    ret = snd_soc_component_set_jack(component, jack, NULL);
> > +    if (ret) {
> > +        dev_warn(component->card->dev, "Failed to set jack: %d\n", ret);
> > +        return ret;
> > +    }
> > +
> > +    return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(snd_soc_usb_setup_offload_jack);
> > +
> >   static int snd_soc_usb_get_offload_card_status(struct snd_kcontrol 
> > *kcontrol,
> >                      struct snd_ctl_elem_value *ucontrol)
> >   {
>
> I'm not sure if this should be handled in generic USB API, this feels 
> like something that should be handled in specific device driver side, 
> like all users currently do.

In some of the previous comments, it was mentioned that maybe it was 
better to have more consistent/defined naming across devices that do 
have support for audio offload.  Initially, I did have these within our 
vendor specific ASoC platform driver also.

> Anyway I think there should also be some function that tears jack down, 
> by calling:
> snd_soc_component_set_jack(component, NULL, NULL);
> so it can get cleaned up properly?

I can add that.  I didn't realize there were some situations where maybe 
components would want to disable the jack.  I will leave the cleanup 
part to ASoC when the platform card is removed.

Thanks
Wesley Cheng