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

[Pierre-Louis Bossart]

> +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.

> +		data->active_idx = card_idx;
> +	} else {
> +		snd_soc_dapm_disable_pin(dapm, "USB_RX_BE");
> +	}
> +	snd_soc_dapm_sync(dapm);
> +
> +	return 0;
> +}