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

[Wesley Cheng <quic_wcheng@quicinc.com>]

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@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.
> 

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;