Re: [PATCH v24 26/34] ALSA: usb-audio: qcom: Don't allow USB offload path if PCM device is in use

On 8/1/2024 1:57 AM, Pierre-Louis Bossart wrote:

On 8/1/24 03:17, 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.

It's a bit weird that the mutual exclusion between the standard path and the offloaded path is handled at the vendor level. I would think this needs to be handled in the soc_usb framework, no?

Hmm...I guess that make sense.  In the end, the mutual exclusion check would need to either be handled by the vendor USB offload driver, or the USB backend DAI link.  I could consider adding another SOC USB API to query for the USB PCM status.  If it is open/active, then just return with an error, or maybe just rename the snd_soc_usb_find_format() API to something more generic which checks for parameters and current status before allowing offloading to start (ie snd_soc_check_offload_available())

Thanks

Wesley Cheng

...

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 8b0913b7256b..3b46d05f1421 100644 --- a/sound/usb/qcom/qc_audio_offload.c +++ b/sound/usb/qcom/qc_audio_offload.c @@ -1460,12 +1460,17 @@ 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,

@@ -1487,6 +1492,11 @@ 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) {

@@ -1510,6 +1520,9 @@ 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);
  

  }

response: