kern/45776: audio freezes on when skipping audio on btsco with mplayer sun audio output

[nathanialsloss%yahoo.com.au@localhost]

>Number:         45776
>Category:       kern
>Synopsis:       audio freezes on when skipping audio on btsco with mplayer sun 
>audio output
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jan 04 15:35:00 +0000 2012
>Originator:     Nat Sloss
>Release:        NetBSD 5.0.1
>Organization:
>Environment:
NetBSD beast 5.0.1 NetBSD 5.0.1 (BEAST) #92: Mon Jan  2 23:55:27 EST 2012  
build@beast:/home/build/NetBSD-5.0.1_source_tree/usr/src/sys/arch/i386/compile/BEAST
 i386
>Description:
When skipping audio with mplayer -ao:sun with btsco bluetooth audio the audio 
output freezes and cannot recover only killed.
>How-To-Repeat:
setup btsco audio. btdev, bthset, scomtu and configuration for ubt sco packets 
etc.

run mplayer -ao sun:/dev/audio[bluetooth audio device number] something.mp3

skip audio with left arrow or up arrow.

The problem also affects NetBSD-5.99.58.
>Fix:
I don't know if I have done the right thing but I noticed that btsco uses 
start_output and start_input,  Other drivers seem to use trigger_output/input.

With experimentation I have found that trigger output is called after skipping 
audio with mplayer but not start_output.

audiostartp is called and then it gets trapped in audio poll endlessly.

So I patched audio.c as follows:

--- audio.c.orig        2009-10-16 16:43:37.000000000 +1100
+++ audio.c     2011-12-22 18:37:47.000000000 +1100
@@ -2559,7 +2559,8 @@
        if (!audio_can_playback(sc))
                return EINVAL;

-       if (!sc->sc_pr.mmapped && used < sc->sc_pr.blksize) {
+       if (!sc->sc_pr.mmapped && used < sc->sc_pr.blksize &&
+           sc->hw_if->trigger_output != NULL) {
                wakeup(&sc->sc_wchan);
                DPRINTF(("%s: wakeup and return\n", __func__));
                return 0;

This means that start_output is called and audio_pint as with trigger_output.  
I fixes the problem but I'm not sure I've done the right thing.

I hope this helps,

Regards,

Nat.