diff options
| author | Hans Petter Selasky <hselasky@FreeBSD.org> | 2016-11-12 17:32:22 +0000 |
|---|---|---|
| committer | Hans Petter Selasky <hselasky@FreeBSD.org> | 2016-11-12 17:32:22 +0000 |
| commit | ac0e0a1a8979978fe97964fe541abfc44fee3c83 (patch) | |
| tree | 7c5c925f6b98a1aac92cecce2b32fdec11a45515 /sys/dev | |
| parent | 8a3ced0f671499a712f0bba23d9ccad87cbaf1f7 (diff) | |
Notes
Diffstat (limited to 'sys/dev')
| -rw-r--r-- | sys/dev/sound/usb/uaudio.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/sys/dev/sound/usb/uaudio.c b/sys/dev/sound/usb/uaudio.c index ca858ff89b54..298f7f72e114 100644 --- a/sys/dev/sound/usb/uaudio.c +++ b/sys/dev/sound/usb/uaudio.c @@ -2047,9 +2047,23 @@ uaudio_chan_play_sync_callback(struct usb_xfer *xfer, usb_error_t error) * Use feedback value as fallback when there is no * recording channel: */ - if (ch->priv_sc->sc_rec_chan.num_alt == 0) - ch->jitter_curr = temp - sample_rate; + if (ch->priv_sc->sc_rec_chan.num_alt == 0) { + int32_t jitter_max = howmany(sample_rate, 16000); + /* + * Range check the jitter values to avoid + * bogus sample rate adjustments. The expected + * deviation should not be more than 1Hz per + * second. The USB v2.0 specification also + * mandates this requirement. Refer to chapter + * 5.12.4.2 about feedback. + */ + ch->jitter_curr = temp - sample_rate; + if (ch->jitter_curr > jitter_max) + ch->jitter_curr = jitter_max; + else if (ch->jitter_curr < -jitter_max) + ch->jitter_curr = -jitter_max; + } ch->feedback_rate = temp; break; |