Hi Pierre, On 8/30/2024 2:45 AM, Pierre-Louis Bossart wrote: > > On 8/29/24 21:40, Wesley Cheng wrote: >> With USB audio offloading, an audio session is started from the ASoC >> platform sound card and PCM devices. Likewise, the USB SND path is still >> readily available for use, in case the non-offload path is desired. In >> order to prevent the two entities from attempting to use the USB bus, >> introduce a flag that determines when either paths are in use. >> >> If a PCM device is already in use, the check will return an error to >> userspace notifying that the stream is currently busy. This ensures that >> only one path is using the USB substream. >> >> Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx> > Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > > I would also move this patch earlier in the series since it has no > dependency on USB offload really, and if somehow it breaks USB audio > regular paths we'd want to know early for bisection. Sure I'll re-order this earlier since I'm going to send out another rev. Thanks Wesley Cheng > >> --- >> sound/usb/card.h | 1 + >> sound/usb/pcm.c | 29 ++++++++++++++++++++++++++--- >> 2 files changed, 27 insertions(+), 3 deletions(-) >> >> diff --git a/sound/usb/card.h b/sound/usb/card.h >> index 15cda1730076..d8b8522e1613 100644 >> --- a/sound/usb/card.h >> +++ b/sound/usb/card.h >> @@ -165,6 +165,7 @@ struct snd_usb_substream { >> unsigned int pkt_offset_adj; /* Bytes to drop from beginning of packets (for non-compliant devices) */ >> unsigned int stream_offset_adj; /* Bytes to drop from beginning of stream (for non-compliant devices) */ >> >> + unsigned int opened:1; /* pcm device opened */ >> unsigned int running: 1; /* running status */ >> unsigned int period_elapsed_pending; /* delay period handling */ >> >> diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c >> index 18467da6fd9e..b24ee38fad72 100644 >> --- a/sound/usb/pcm.c >> +++ b/sound/usb/pcm.c >> @@ -1241,8 +1241,17 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream) >> struct snd_usb_stream *as = snd_pcm_substream_chip(substream); >> struct snd_pcm_runtime *runtime = substream->runtime; >> struct snd_usb_substream *subs = &as->substream[direction]; >> + struct snd_usb_audio *chip = subs->stream->chip; >> int ret; >> >> + mutex_lock(&chip->mutex); >> + if (subs->opened) { >> + mutex_unlock(&chip->mutex); >> + return -EBUSY; >> + } >> + subs->opened = 1; >> + mutex_unlock(&chip->mutex); >> + >> runtime->hw = snd_usb_hardware; >> /* need an explicit sync to catch applptr update in low-latency mode */ >> if (direction == SNDRV_PCM_STREAM_PLAYBACK && >> @@ -1259,13 +1268,23 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream) >> >> ret = setup_hw_info(runtime, subs); >> if (ret < 0) >> - return ret; >> + goto err_open; >> ret = snd_usb_autoresume(subs->stream->chip); >> if (ret < 0) >> - return ret; >> + goto err_open; >> ret = snd_media_stream_init(subs, as->pcm, direction); >> if (ret < 0) >> - snd_usb_autosuspend(subs->stream->chip); >> + goto err_resume; >> + >> + return 0; >> + >> +err_resume: >> + snd_usb_autosuspend(subs->stream->chip); >> +err_open: >> + mutex_lock(&chip->mutex); >> + subs->opened = 0; >> + mutex_unlock(&chip->mutex); >> + >> return ret; >> } >> >> @@ -1274,6 +1293,7 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream) >> int direction = substream->stream; >> struct snd_usb_stream *as = snd_pcm_substream_chip(substream); >> struct snd_usb_substream *subs = &as->substream[direction]; >> + struct snd_usb_audio *chip = subs->stream->chip; >> int ret; >> >> snd_media_stop_pipeline(subs); >> @@ -1287,6 +1307,9 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream) >> >> subs->pcm_substream = NULL; >> snd_usb_autosuspend(subs->stream->chip); >> + mutex_lock(&chip->mutex); >> + subs->opened = 0; >> + mutex_unlock(&chip->mutex); >> >> return 0; >> }