On Wed, Apr 09, 2025 at 12:47:59PM -0700, Wesley Cheng wrote:
> The USB SND path may need to know how the USB offload path is routed, so
> that applications can open the proper sound card and PCM device. The
> implementation for the QC ASoC design has a "USB Mixer" kcontrol for each
Is this "USB_RX Audio Mixer" now?
> possible FE (Q6ASM) DAI, which can be utilized to know which front end link
> is enabled.
>
> When an application/userspace queries for the mapped offload devices, the
> logic will lookup the USB mixer status though the following path:
>
> MultiMedia* <-> MM_DL* <-> USB Mixer*
^
>
> The "USB Mixer" is a DAPM widget, and the q6routing entity will set the
^
> DAPM connect status accordingly if the USB mixer is enabled. If enabled,
> the Q6USB backend link can fetch the PCM device number from the FE DAI
> link (Multimedia*). With respects to the card number, that is
> straightforward, as the ASoC components have direct references to the ASoC
> platform sound card.
>
> An example output can be shown below:
>
> Number of controls: 9
> name value
> Capture Channel Map 0, 0 (range 0->36)
> Playback Channel Map 0, 0 (range 0->36)
> Headset Capture Switch On
> Headset Capture Volume 1 (range 0->4)
> Sidetone Playback Switch On
> Sidetone Playback Volume 4096 (range 0->8192)
> Headset Playback Switch On
> Headset Playback Volume 20, 20 (range 0->24)
> USB Offload Playback Route PCM#0 0, 1 (range -1->255)
>
> The "USB Offload Playback Route PCM#*" kcontrol will signify the
> corresponding card and pcm device it is offload to. (card#0 pcm - device#1)
> If the USB SND device supports multiple audio interfaces, then it will
> contain several PCM streams, hence in those situations, it is expected
> that there will be multiple playback route kcontrols created.
>
> Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> ---
> sound/soc/qcom/qdsp6/q6usb.c | 98 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 98 insertions(+)
>
> diff --git a/sound/soc/qcom/qdsp6/q6usb.c b/sound/soc/qcom/qdsp6/q6usb.c
> index 6634e132787e..274c251e84dd 100644
> --- a/sound/soc/qcom/qdsp6/q6usb.c
> +++ b/sound/soc/qcom/qdsp6/q6usb.c
> @@ -134,6 +134,103 @@ static int q6usb_audio_ports_of_xlate_dai_name(struct snd_soc_component *compone
> return ret;
> }
>
> +static int q6usb_get_pcm_id_from_widget(struct snd_soc_dapm_widget *w)
> +{
> + struct snd_soc_pcm_runtime *rtd;
> + struct snd_soc_dai *dai;
> +
> + for_each_card_rtds(w->dapm->card, rtd) {
> + dai = snd_soc_rtd_to_cpu(rtd, 0);
> + /*
> + * Only look for playback widget. RTD number carries the assigned
> + * PCM index.
> + */
> + if (dai->stream[0].widget == w)
> + return rtd->id;
> + }
> +
> + return -1;
> +}
> +
> +static int q6usb_usb_mixer_enabled(struct snd_soc_dapm_widget *w)
> +{
> + struct snd_soc_dapm_path *p;
> +
> + /* Checks to ensure USB path is enabled/connected */
> + snd_soc_dapm_widget_for_each_sink_path(w, p)
> + if (!strcmp(p->sink->name, "USB Mixer") && p->connect)
> + return 1;
I assume this also needs to be changed. Please make sure you test the
series again. :)
> +
> + return 0;
> +}
> +
> +static int q6usb_get_pcm_id(struct snd_soc_component *component)
> +{
> + struct snd_soc_dapm_widget *w;
> + struct snd_soc_dapm_path *p;
> + int pidx;
> +
> + /*
> + * Traverse widgets to find corresponding FE widget. The DAI links are
> + * built like the following:
> + * MultiMedia* <-> MM_DL* <-> USB Mixer*
^
Thanks,
Stephan
