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Date:   Wed, 4 Jan 2023 17:41:22 -0600
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Subject: Re: [RFC PATCH 03/14] ASoC: qcom: Add USB backend ASoC driver for Q6
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To:     Wesley Cheng <quic_wcheng@quicinc.com>,
        srinivas.kandagatla@linaro.org, mathias.nyman@intel.com,
        perex@perex.cz, broonie@kernel.org, lgirdwood@gmail.com,
        andersson@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        gregkh@linuxfoundation.org, Thinh.Nguyen@synopsys.com,
        bgoswami@quicinc.com, tiwai@suse.com, robh+dt@kernel.org,
        agross@kernel.org
Cc:     devicetree@vger.kernel.org, alsa-devel@alsa-project.org,
        linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, quic_jackp@quicinc.com,
        quic_plai@quicinc.com
References: <20221223233200.26089-1-quic_wcheng@quicinc.com>
 <20221223233200.26089-4-quic_wcheng@quicinc.com>
From:   Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
In-Reply-To: <20221223233200.26089-4-quic_wcheng@quicinc.com>
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> +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;
> +}