[pulseaudio-discuss] [RFC PATCH 1/2] pulsecore: sink: force suspend/resume on passthrough transitions

[Pierre-Louis Bossart]

A race condition prevents the AES non-audio bit from being set
when enabling IEC61937 passthrough on resume with no sink-input
connected (pa_sink_is_passthrough returns false). The non-audio
bit should really be set when opening the sink.

Force the sink to suspend/resume when actually entering passthrough
mode, and likewise force a suspend-resume on leaving passthrough mode.

Tested with E-AC3 streams which do need the AES bit set for my
Onkyon receiver to detect the format instead of playing it as
PCM.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 src/pulsecore/sink.c | 24 ++++++++++++++++++++++++
 src/pulsecore/sink.h |  1 +
 2 files changed, 25 insertions(+)

diff --git a/src/pulsecore/sink.c b/src/pulsecore/sink.c
index a8b4cd3..0cc7651 100644
--- a/src/pulsecore/sink.c
+++ b/src/pulsecore/sink.c
@@ -1626,6 +1626,11 @@ bool pa_sink_is_passthrough(pa_sink *s) {
 void pa_sink_enter_passthrough(pa_sink *s) {
     pa_cvolume volume;
 
+    if (s->is_passthrough_set) {
+	pa_log_debug("Sink %s is already in passthrough mode, nothing to do", s->name);
+	return;
+    }
+
     /* disable the monitor in passthrough mode */
     if (s->monitor_source) {
         pa_log_debug("Suspending monitor source %s, because the sink is entering the passthrough mode.", s->monitor_source->name);
@@ -1638,10 +1643,23 @@ void pa_sink_enter_passthrough(pa_sink *s) {
 
     pa_cvolume_set(&volume, s->sample_spec.channels, PA_MIN(s->base_volume, PA_VOLUME_NORM));
     pa_sink_set_volume(s, &volume, true, false);
+
+    pa_log_debug("Suspending/Restarting sink %s to enter passthrough mode", s->name);
+
+    /* force sink to be resumed in passthrough mode */
+    pa_sink_suspend(s, true, PA_SUSPEND_INTERNAL);
+    s->is_passthrough_set = true;
+    pa_sink_suspend(s, false, PA_SUSPEND_INTERNAL);
 }
 
 /* Called from main context */
 void pa_sink_leave_passthrough(pa_sink *s) {
+
+    if (!s->is_passthrough_set) {
+	pa_log_debug("Sink %s is not in passthrough mode, nothing to do", s->name);
+	return;
+    }
+
     /* Unsuspend monitor */
     if (s->monitor_source) {
         pa_log_debug("Resuming monitor source %s, because the sink is leaving the passthrough mode.", s->monitor_source->name);
@@ -1653,6 +1671,12 @@ void pa_sink_leave_passthrough(pa_sink *s) {
 
     pa_cvolume_init(&s->saved_volume);
     s->saved_save_volume = false;
+
+    /* force sink to be resumed in non-passthrough mode */
+    pa_sink_suspend(s, true, PA_SUSPEND_INTERNAL);
+    s->is_passthrough_set = false;
+    pa_sink_suspend(s, false, PA_SUSPEND_INTERNAL);
+
 }
 
 /* Called from main context. */
diff --git a/src/pulsecore/sink.h b/src/pulsecore/sink.h
index 0e79cf3..7deafdd 100644
--- a/src/pulsecore/sink.h
+++ b/src/pulsecore/sink.h
@@ -108,6 +108,7 @@ struct pa_sink {
     /* Saved volume state while we're in passthrough mode */
     pa_cvolume saved_volume;
     bool saved_save_volume:1;
+    bool is_passthrough_set:1;
 
     pa_asyncmsgq *asyncmsgq;
 
-- 
2.9.3