Re: [RFC PATCH 03/14] ASoC: qcom: Add USB backend ASoC driver for Q6

[Wesley Cheng]

Hi Pierre,

On 1/4/2023 3:41 PM, Pierre-Louis Bossart wrote:
> > +int q6usb_alsa_connection_cb(struct snd_soc_usb *usb, int card_idx,
> > +			int connected)
> > +{
> > +	struct snd_soc_dapm_context *dapm;
> > +	struct q6usb_port_data *data;
> > +
> > +	if (!usb->component)
> > +		return 0;
> > +
> > +	dapm = snd_soc_component_get_dapm(usb->component);
> > +	data = dev_get_drvdata(usb->component->dev);
> > +
> > +	if (connected) {
> > +		snd_soc_dapm_enable_pin(dapm, "USB_RX_BE");
> > +		/* We only track the latest USB headset plugged in */
>
> that answers to my earlier question on how to deal with multiple
> devices, but is this a desirable policy? This could lead to a lot of
> confusion. If there are restrictions to a single device, then it might
> be more interesting for userspace or the user to indicate which USB
> device gets to use USB offload and all others use legacy.

Yeah, as mentioned its still pretty open ended.  I think from the 
feedback received from Mark/Takashi, this was a viable option for now. 
Would you happen to have any insight/input on how the userspace can pass 
down that selection to the ASoC framework?  Maybe some kind of PCM IOCTL 
call?

Thanks
Wesley Cheng