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

Takashi Iwai
2026-04-17T08:49:12Z

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