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| author | Takashi Iwai <tiwai@suse.de> | 2021-09-29 10:08:39 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2021-09-30 13:55:21 +0200 |
| commit | e581f1cec4f899f788f6c9477f805b1d5fef25e2 (patch) | |
| tree | d240f79e8c5befe3fd7a59a785b7398f584fa404 /sound/usb | |
| parent | ALSA: usb-audio: Rename early_playback_start flag with lowlatency_playback (diff) | |
| download | linux-e581f1cec4f899f788f6c9477f805b1d5fef25e2.tar.xz linux-e581f1cec4f899f788f6c9477f805b1d5fef25e2.zip | |
ALSA: usb-audio: Disable low-latency playback for free-wheel mode
The free-wheel stream operation like dmix may not update the appl_ptr
appropriately, and it doesn't fit with the low-latency playback mode.
Disable the low-latency playback operation when the stream is set up
in such a mode.
Link: https://lore.kernel.org/r/20210929080844.11583-5-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb')
| -rw-r--r-- | sound/usb/pcm.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 4dd7f1c9e2af..84b03a32ee23 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -582,7 +582,8 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream) } /* check whether early start is needed for playback stream */ -static int lowlatency_playback_available(struct snd_usb_substream *subs) +static int lowlatency_playback_available(struct snd_pcm_runtime *runtime, + struct snd_usb_substream *subs) { struct snd_usb_audio *chip = subs->stream->chip; @@ -591,6 +592,9 @@ static int lowlatency_playback_available(struct snd_usb_substream *subs) /* disabled via module option? */ if (!chip->lowlatency) return false; + /* free-wheeling mode? (e.g. dmix) */ + if (runtime->stop_threshold > runtime->buffer_size) + return false; /* too short periods? */ if (subs->data_endpoint->nominal_queue_size >= subs->buffer_bytes) return false; @@ -630,7 +634,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream) subs->period_elapsed_pending = 0; runtime->delay = 0; - subs->lowlatency_playback = lowlatency_playback_available(subs); + subs->lowlatency_playback = lowlatency_playback_available(runtime, subs); if (!subs->lowlatency_playback) ret = start_endpoints(subs); |