[PATCH] ALSA: usb-audio: qcom: move offload usage counting to stream request handler

[PATCH] ALSA: usb-audio: qcom: move offload usage counting to stream request handler

[Guan-Yu Lin]

Centralize usb_offload_get()/usb_offload_put() calls from various helper
functions to handle_uaudio_stream_req(), which ensures the usage count
is tied directly to the QMI stream enable/dsiable requests from audio
DSP. Such design provides a clear synchronization point for the
offloading lifecycle and correctly balances the count for both playback
and capture paths while avoiding redundant increments during auxiliary
operations.

Suggested-by: Wesley Cheng <wesley.cheng@oss.qualcomm.com>
Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
---
 sound/usb/qcom/qc_audio_offload.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c
index 2ac813d57f4f..cddab55d4691 100644
--- a/sound/usb/qcom/qc_audio_offload.c
+++ b/sound/usb/qcom/qc_audio_offload.c
@@ -699,7 +699,6 @@ static void uaudio_event_ring_cleanup_free(struct uaudio_dev *dev)
 		uaudio_iommu_unmap(MEM_EVENT_RING, IOVA_BASE, PAGE_SIZE,
 				   PAGE_SIZE);
 		xhci_sideband_remove_interrupter(uadev[dev->chip->card->number].sb);
-		usb_offload_put(dev->udev);
 	}
 }
 
@@ -1183,16 +1182,12 @@ static int uaudio_event_ring_setup(struct snd_usb_substream *subs,
 	dma_coherent = dev_is_dma_coherent(subs->dev->bus->sysdev);
 	er_pa = 0;
 
-	ret = usb_offload_get(subs->dev);
-	if (ret < 0)
-		goto exit;
-
 	/* event ring */
 	ret = xhci_sideband_create_interrupter(uadev[card_num].sb, 1, false,
 					       0, uaudio_qdev->data->intr_num);
 	if (ret < 0) {
 		dev_err(&subs->dev->dev, "failed to fetch interrupter\n");
-		goto put_offload;
+		goto exit;
 	}
 
 	sgt = xhci_sideband_get_event_buffer(uadev[card_num].sb);
@@ -1224,8 +1219,6 @@ static int uaudio_event_ring_setup(struct snd_usb_substream *subs,
 	mem_info->dma = 0;
 remove_interrupter:
 	xhci_sideband_remove_interrupter(uadev[card_num].sb);
-put_offload:
-	usb_offload_put(subs->dev);
 exit:
 	return ret;
 }
@@ -1489,7 +1482,6 @@ static int prepare_qmi_response(struct snd_usb_substream *subs,
 	uaudio_iommu_unmap(MEM_EVENT_RING, IOVA_BASE, PAGE_SIZE, PAGE_SIZE);
 free_sec_ring:
 	xhci_sideband_remove_interrupter(uadev[card_num].sb);
-	usb_offload_put(subs->dev);
 drop_sync_ep:
 	if (subs->sync_endpoint) {
 		uaudio_iommu_unmap(MEM_XFER_RING,
@@ -1605,6 +1597,12 @@ static void handle_uaudio_stream_req(struct qmi_handle *handle,
 	uadev[pcm_card_num].ctrl_intf = chip->ctrl_intf;
 
 	if (req_msg->enable) {
+		ret = usb_offload_get(subs->dev);
+		if (ret < 0) {
+			guard(mutex)(&chip->mutex);
+			subs->opened = 0;
+			goto response;
+		}
 		ret = enable_audio_stream(subs,
 					  map_pcm_format(req_msg->audio_format),
 					  req_msg->number_of_ch, req_msg->bit_rate,
@@ -1658,9 +1656,11 @@ static void handle_uaudio_stream_req(struct qmi_handle *handle,
 			uaudio_dev_intf_cleanup(uadev[pcm_card_num].udev,
 						info);
 		}
-		if (atomic_read(&uadev[pcm_card_num].in_use))
+		if (atomic_read(&uadev[pcm_card_num].in_use)) {
 			kref_put(&uadev[pcm_card_num].kref,
 				 uaudio_dev_release);
+			usb_offload_put(subs->dev);
+		}
 	}
 	mutex_unlock(&qdev_mutex);
 
-- 
2.54.0.rc1.513.gad8abe7a5a-goog

Re: [PATCH] ALSA: usb-audio: qcom: move offload usage counting to stream request handler

[Takashi Iwai]

On Fri, 17 Apr 2026 07:43:30 +0200,
Guan-Yu Lin wrote:
> 
> Centralize usb_offload_get()/usb_offload_put() calls from various helper
> functions to handle_uaudio_stream_req(), which ensures the usage count
> is tied directly to the QMI stream enable/dsiable requests from audio
> DSP. Such design provides a clear synchronization point for the
> offloading lifecycle and correctly balances the count for both playback
> and capture paths while avoiding redundant increments during auxiliary
> operations.
> 
> Suggested-by: Wesley Cheng <wesley.cheng@oss.qualcomm.com>
> Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
> ---
>  sound/usb/qcom/qc_audio_offload.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c
> index 2ac813d57f4f..cddab55d4691 100644
> --- a/sound/usb/qcom/qc_audio_offload.c
> +++ b/sound/usb/qcom/qc_audio_offload.c
> @@ -699,7 +699,6 @@ static void uaudio_event_ring_cleanup_free(struct uaudio_dev *dev)
>  		uaudio_iommu_unmap(MEM_EVENT_RING, IOVA_BASE, PAGE_SIZE,
>  				   PAGE_SIZE);
>  		xhci_sideband_remove_interrupter(uadev[dev->chip->card->number].sb);
> -		usb_offload_put(dev->udev);
>  	}
>  }
>  
> @@ -1183,16 +1182,12 @@ static int uaudio_event_ring_setup(struct snd_usb_substream *subs,
>  	dma_coherent = dev_is_dma_coherent(subs->dev->bus->sysdev);
>  	er_pa = 0;
>  
> -	ret = usb_offload_get(subs->dev);
> -	if (ret < 0)
> -		goto exit;
> -
>  	/* event ring */
>  	ret = xhci_sideband_create_interrupter(uadev[card_num].sb, 1, false,
>  					       0, uaudio_qdev->data->intr_num);
>  	if (ret < 0) {
>  		dev_err(&subs->dev->dev, "failed to fetch interrupter\n");
> -		goto put_offload;
> +		goto exit;
>  	}
>  
>  	sgt = xhci_sideband_get_event_buffer(uadev[card_num].sb);
> @@ -1224,8 +1219,6 @@ static int uaudio_event_ring_setup(struct snd_usb_substream *subs,
>  	mem_info->dma = 0;
>  remove_interrupter:
>  	xhci_sideband_remove_interrupter(uadev[card_num].sb);
> -put_offload:
> -	usb_offload_put(subs->dev);
>  exit:
>  	return ret;
>  }
> @@ -1489,7 +1482,6 @@ static int prepare_qmi_response(struct snd_usb_substream *subs,
>  	uaudio_iommu_unmap(MEM_EVENT_RING, IOVA_BASE, PAGE_SIZE, PAGE_SIZE);
>  free_sec_ring:
>  	xhci_sideband_remove_interrupter(uadev[card_num].sb);
> -	usb_offload_put(subs->dev);
>  drop_sync_ep:
>  	if (subs->sync_endpoint) {
>  		uaudio_iommu_unmap(MEM_XFER_RING,
> @@ -1605,6 +1597,12 @@ static void handle_uaudio_stream_req(struct qmi_handle *handle,
>  	uadev[pcm_card_num].ctrl_intf = chip->ctrl_intf;
>  
>  	if (req_msg->enable) {
> +		ret = usb_offload_get(subs->dev);
> +		if (ret < 0) {
> +			guard(mutex)(&chip->mutex);
> +			subs->opened = 0;
> +			goto response;
> +		}
>  		ret = enable_audio_stream(subs,
>  					  map_pcm_format(req_msg->audio_format),
>  					  req_msg->number_of_ch, req_msg->bit_rate,

I think the usb_offload_put() is missing at the error handling of the
call above?


thanks,

Takashi