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

Guan-Yu Lin
2026-04-17T05:46:45Z

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