Re: [PATCH v9 28/34] ASoC: qcom: qdsp6: Add support to track available USB PCM devices

[Wesley Cheng]

Hi Pierre,

On 10/17/2023 3:43 PM, Pierre-Louis Bossart wrote:
> On 10/17/23 15:01, Wesley Cheng wrote:
> > The USB backend should know about which sound resources are being shared
> > between the ASoC and USB SND paths.  This can be utilized to properly
> > select and maintain the offloading devices.
> >
> > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> > ---
> >   sound/soc/qcom/qdsp6/q6usb.c | 16 ++++++++++++++++
> >   1 file changed, 16 insertions(+)
> >
> > diff --git a/sound/soc/qcom/qdsp6/q6usb.c b/sound/soc/qcom/qdsp6/q6usb.c
> > index 329a7d4a3c01..d697cbe7f184 100644
> > --- a/sound/soc/qcom/qdsp6/q6usb.c
> > +++ b/sound/soc/qcom/qdsp6/q6usb.c
> > @@ -25,10 +25,18 @@
> >   
> >   #define SID_MASK	0xF
> >   
> > +struct q6usb_status {
> > +	unsigned int num_pcm;
>
> how would one know which ones are capture and which ones are playback?
>
> This really looks like a playback-only assumption, despite earlier
> mentions of capture supported.

Yes, playback only, which is the reasoning for only having one parameter 
here.  I will rename it though to be clearer.

Thanks
Wesley Cheng

> > +	unsigned int chip_index;
> > +	unsigned int pcm_index;
> > +};
> > +
> >   struct q6usb_port_data {
> >   	struct q6afe_usb_cfg usb_cfg;
> >   	struct snd_soc_usb *usb;
> >   	struct q6usb_offload priv;
> > +	unsigned long available_card_slot;
> > +	struct q6usb_status status[SNDRV_CARDS];
> >   	int active_idx;
> >   };
> >   
> > @@ -110,6 +118,14 @@ static int q6usb_alsa_connection_cb(struct snd_soc_usb *usb,
> >   	if (connected) {
> >   		/* We only track the latest USB headset plugged in */
> >   		data->active_idx = sdev->card_idx;
> > +
> > +		set_bit(sdev->card_idx, &data->available_card_slot);
> > +		data->status[sdev->card_idx].num_pcm = sdev->num_playback;
>
> there you go...
>
> > +		data->status[sdev->card_idx].chip_index = sdev->chip_idx;
> > +	} else {
> > +		clear_bit(sdev->card_idx, &data->available_card_slot);
> > +		data->status[sdev->card_idx].num_pcm = 0;
> > +		data->status[sdev->card_idx].chip_index = 0;
> >   	}
> >   
> >   	return 0;