diff options
Diffstat (limited to 'sound/usb/pcm.c')
| -rw-r--r-- | sound/usb/pcm.c | 29 |
1 files changed, 20 insertions, 9 deletions
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 19392117de9e..4dd7f1c9e2af 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -581,6 +581,22 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream) return 0; } +/* check whether early start is needed for playback stream */ +static int lowlatency_playback_available(struct snd_usb_substream *subs) +{ + struct snd_usb_audio *chip = subs->stream->chip; + + if (subs->direction == SNDRV_PCM_STREAM_CAPTURE) + return false; + /* disabled via module option? */ + if (!chip->lowlatency) + return false; + /* too short periods? */ + if (subs->data_endpoint->nominal_queue_size >= subs->buffer_bytes) + return false; + return true; +} + /* * prepare callback * @@ -614,13 +630,8 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream) subs->period_elapsed_pending = 0; runtime->delay = 0; - /* check whether early start is needed for playback stream */ - subs->early_playback_start = - subs->direction == SNDRV_PCM_STREAM_PLAYBACK && - (!chip->lowlatency || - (subs->data_endpoint->nominal_queue_size >= subs->buffer_bytes)); - - if (subs->early_playback_start) + subs->lowlatency_playback = lowlatency_playback_available(subs); + if (!subs->lowlatency_playback) ret = start_endpoints(subs); unlock: @@ -1412,7 +1423,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs, subs->trigger_tstamp_pending_update = false; } - if (period_elapsed && !subs->running && !subs->early_playback_start) { + if (period_elapsed && !subs->running && subs->lowlatency_playback) { subs->period_elapsed_pending = 1; period_elapsed = 0; } @@ -1466,7 +1477,7 @@ static int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substrea prepare_playback_urb, retire_playback_urb, subs); - if (!subs->early_playback_start && + if (subs->lowlatency_playback && cmd == SNDRV_PCM_TRIGGER_START) { err = start_endpoints(subs); if (err < 0) { |