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| author |   Takashi Iwai <tiwai@suse.de> | 2021-09-29 10:08:40 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2021-09-30 13:55:22 +0200 |
| commit | bceee75387554f682638e719d1ea60125ea78cea (patch) | |
| tree | 89a367c7c3b2e7e684eb567e4e4f5e3b6733856a /sound/usb/pcm.c | |
| parent | ALSA: usb-audio: Disable low-latency playback for free-wheel mode (diff) | |
| download | linux-dev-bceee75387554f682638e719d1ea60125ea78cea.tar.xz linux-dev-bceee75387554f682638e719d1ea60125ea78cea.zip | |
ALSA: usb-audio: Disable low-latency mode for implicit feedback sync
When a playback stream runs in the implicit feedback mode, its
operation is passive and won't start unless the capture packet is
received. This behavior contradicts with the low-latency playback
mode, and we should turn off lowlatency_playback flag accordingly.
In theory, we may take the low-latency mode when the playback-first
quirk is set, but it still conflicts with the later operation with the
fixed packet numbers, so it's disabled all together for now.
Link: https://lore.kernel.org/r/20210929080844.11583-6-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb/pcm.c')
| -rw-r--r-- | sound/usb/pcm.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 84b03a32ee23..ec7eeb1b82b8 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -595,6 +595,9 @@ static int lowlatency_playback_available(struct snd_pcm_runtime *runtime, /* free-wheeling mode? (e.g. dmix) */ if (runtime->stop_threshold > runtime->buffer_size) return false; + /* implicit feedback mode has own operation mode */ + if (snd_usb_endpoint_implicit_feedback_sink(subs->data_endpoint)) + return false; /* too short periods? */ if (subs->data_endpoint->nominal_queue_size >= subs->buffer_bytes) return false; |