Re: [PATCH v26 29/33] ALSA: usb-audio: qcom: Don't allow USB offload path if PCM device is in use

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

On 8/29/24 21:41, Wesley Cheng wrote:
> Add proper checks and updates to the USB substream once receiving a USB QMI
> stream enable request.  If the substream is already in use from the non
> offload path, reject the stream enable request.  In addition, update the
> USB substream opened parameter when enabling the offload path, so the
> non offload path can be blocked.
> 
> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
> ---
>  sound/usb/qcom/qc_audio_offload.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c
> index e9f2fd6bbb41..0bd533f539e4 100644
> --- a/sound/usb/qcom/qc_audio_offload.c
> +++ b/sound/usb/qcom/qc_audio_offload.c
> @@ -1482,12 +1482,17 @@ static void handle_uaudio_stream_req(struct qmi_handle *handle,
>  		goto response;
>  	}
>  
> +	mutex_lock(&chip->mutex);
>  	if (req_msg->enable) {
> -		if (info_idx < 0 || chip->system_suspend) {
> +		if (info_idx < 0 || chip->system_suspend || subs->opened) {
>  			ret = -EBUSY;
> +			mutex_unlock(&chip->mutex);
> +
>  			goto response;
>  		}
> +		subs->opened = 1;
>  	}
> +	mutex_unlock(&chip->mutex);
>  
>  	if (req_msg->service_interval_valid) {
>  		ret = get_data_interval_from_si(subs,
> @@ -1509,6 +1514,11 @@ static void handle_uaudio_stream_req(struct qmi_handle *handle,
>  		if (!ret)
>  			ret = prepare_qmi_response(subs, req_msg, &resp,
>  						   info_idx);
> +		if (ret < 0) {
> +			mutex_lock(&chip->mutex);
> +			subs->opened = 0;
> +			mutex_unlock(&chip->mutex);
> +		}
>  	} else {
>  		info = &uadev[pcm_card_num].info[info_idx];
>  		if (info->data_ep_pipe) {
> @@ -1532,6 +1542,9 @@ static void handle_uaudio_stream_req(struct qmi_handle *handle,
>  		}
>  
>  		disable_audio_stream(subs);
> +		mutex_lock(&chip->mutex);
> +		subs->opened = 0;
> +		mutex_unlock(&chip->mutex);
>  	}
>  


This sounds ok but I wonder why all this needs to be done in
Qualcomm-specific layers instead of soc-usb?