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.
Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/pcm.c | 3 +++ 1 file changed, 3 insertions(+)
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;