The branch main has been updated by christos: URL: https://cgit.FreeBSD.org/src/commit/?id=5e02679f03cda224f59adcf83d5308fffa6d11a1
commit 5e02679f03cda224f59adcf83d5308fffa6d11a1 Author: Christos Margiolis <[email protected]> AuthorDate: 2026-09-07 13:04:09 +0000 Commit: Christos Margiolis <[email protected]> CommitDate: 2026-09-07 13:04:09 +0000 sound: Prefer idle primary channels when allocating dsp_chn_alloc() stopped at the first primary channel that was either idle or already had vchans. Since the list is walked in order, the first channel matched both conditions once it had been used, so every client after the first was stacked onto it as a vchan and the remaining primary channels were never allocated at all. This is invisible on devices with a single primary channel, but not on those which provide several. snd_emu10kx(4), for instance, registers four primary channels for its front device, each able to run with its own rate. Look for an idle primary channel first, and only fall back to sharing one that already has vchans when there is none left. Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Reviewed by: markj Differential Revision: https://reviews.freebsd.org/D59084 --- sys/dev/sound/pcm/dsp.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/sys/dev/sound/pcm/dsp.c b/sys/dev/sound/pcm/dsp.c index c92c55b02cff..d32f83e3ae76 100644 --- a/sys/dev/sound/pcm/dsp.c +++ b/sys/dev/sound/pcm/dsp.c @@ -186,18 +186,28 @@ dsp_chn_alloc(struct snddev_info *d, struct pcm_channel **ch, int direction, (direction == PCMDIR_REC && d->flags & SD_F_RVCHANS); *ch = NULL; + + /* + * Prefer an idle primary channel, so that devices which provide more + * than one of them use them all, instead of stacking every client on + * the first one. + */ CHN_FOREACH(c, d, channels.pcm.primary) { CHN_LOCK(c); - if (c->direction != direction) { - CHN_UNLOCK(c); - continue; - } - /* Find an available primary channel to use. */ - if ((c->flags & CHN_F_BUSY) == 0 || - (vdir_enabled && (c->flags & CHN_F_HAS_VCHAN))) + if (c->direction == direction && (c->flags & CHN_F_BUSY) == 0) break; CHN_UNLOCK(c); } + /* Fall back to sharing a primary channel that already has vchans. */ + if (c == NULL && vdir_enabled) { + CHN_FOREACH(c, d, channels.pcm.primary) { + CHN_LOCK(c); + if (c->direction == direction && + (c->flags & CHN_F_HAS_VCHAN)) + break; + CHN_UNLOCK(c); + } + } if (c == NULL) return (EBUSY);
