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

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

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@quicinc.com>
> ---
>  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.

> +	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;