alsa: support fixed latency range in alsa modules

This adds a boolean module parameter to disable automatic dynamic
latency readjustments on underruns, but leaves automatic dynamic
watermark readjustments untouched.

diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c
index 7b31b1b55825b71c320b317e841ccdfc1e5f0475..1386196282c4e690da41a053f5eae943bc11c130 100644 (file)
--- a/src/modules/alsa/alsa-sink.c
+++ b/src/modules/alsa/alsa-sink.c
@@ -134,7 +134,7 @@ struct userdata {
     char *device_name;  /* name of the PCM device */
     char *control_device; /* name of the control device */
 
-    pa_bool_t use_mmap:1, use_tsched:1, deferred_volume:1;
+    pa_bool_t use_mmap:1, use_tsched:1, deferred_volume:1, fixed_latency_range:1;
 
     pa_bool_t first, after_rewind;
 
@@ -331,7 +331,12 @@ static void increase_watermark(struct userdata *u) {
         return;
     }
 
-    /* Hmm, we cannot increase the watermark any further, hence let's raise the latency */
+    /* Hmm, we cannot increase the watermark any further, hence let's
+       raise the latency, unless doing so was disabled in
+       configuration */
+    if (u->fixed_latency_range)
+        return;
+
     old_min_latency = u->sink->thread_info.min_latency;
     new_min_latency = PA_MIN(old_min_latency * 2, old_min_latency + TSCHED_WATERMARK_INC_STEP_USEC);
     new_min_latency = PA_MIN(new_min_latency, u->sink->thread_info.max_latency);
@@ -1969,7 +1974,7 @@ pa_sink *pa_alsa_sink_new(pa_module *m, pa_modargs *ma, const char*driver, pa_ca
     uint32_t nfrags, frag_size, buffer_size, tsched_size, tsched_watermark, rewind_safeguard;
     snd_pcm_uframes_t period_frames, buffer_frames, tsched_frames;
     size_t frame_size;
-    pa_bool_t use_mmap = TRUE, b, use_tsched = TRUE, d, ignore_dB = FALSE, namereg_fail = FALSE, deferred_volume = FALSE, set_formats = FALSE;
+    pa_bool_t use_mmap = TRUE, b, use_tsched = TRUE, d, ignore_dB = FALSE, namereg_fail = FALSE, deferred_volume = FALSE, set_formats = FALSE, fixed_latency_range = FALSE;
     pa_sink_new_data data;
     pa_alsa_profile_set *profile_set = NULL;
 
@@ -2039,6 +2044,11 @@ pa_sink *pa_alsa_sink_new(pa_module *m, pa_modargs *ma, const char*driver, pa_ca
         goto fail;
     }
 
+    if (pa_modargs_get_value_boolean(ma, "fixed_latency_range", &fixed_latency_range) < 0) {
+        pa_log("Failed to parse fixed_latency_range argument.");
+        goto fail;
+    }
+
     use_tsched = pa_alsa_may_tsched(use_tsched);
 
     u = pa_xnew0(struct userdata, 1);
@@ -2047,6 +2057,7 @@ pa_sink *pa_alsa_sink_new(pa_module *m, pa_modargs *ma, const char*driver, pa_ca
     u->use_mmap = use_mmap;
     u->use_tsched = use_tsched;
     u->deferred_volume = deferred_volume;
+    u->fixed_latency_range = fixed_latency_range;
     u->first = TRUE;
     u->rewind_safeguard = rewind_safeguard;
     u->rtpoll = pa_rtpoll_new();
@@ -2143,9 +2154,13 @@ pa_sink *pa_alsa_sink_new(pa_module *m, pa_modargs *ma, const char*driver, pa_ca
     if (u->use_mmap)
         pa_log_info("Successfully enabled mmap() mode.");
 
-    if (u->use_tsched)
+    if (u->use_tsched) {
         pa_log_info("Successfully enabled timer-based scheduling mode.");
 
+        if (u->fixed_latency_range)
+            pa_log_info("Disabling latency range changes on underrun");
+    }
+
     if (is_iec958(u) || is_hdmi(u))
         set_formats = TRUE;
 

diff --git a/src/modules/alsa/alsa-source.c b/src/modules/alsa/alsa-source.c
index 7a51572c839605b1faf1e8156775ab91785e2a0d..255a61d649b743c20a8ccda3b2834fba3f32ec04 100644 (file)
--- a/src/modules/alsa/alsa-source.c
+++ b/src/modules/alsa/alsa-source.c
@@ -121,7 +121,7 @@ struct userdata {
     char *device_name;  /* name of the PCM device */
     char *control_device; /* name of the control device */
 
-    pa_bool_t use_mmap:1, use_tsched:1, deferred_volume:1;
+    pa_bool_t use_mmap:1, use_tsched:1, deferred_volume:1, fixed_latency_range:1;
 
     pa_bool_t first;
 
@@ -306,7 +306,12 @@ static void increase_watermark(struct userdata *u) {
         return;
     }
 
-    /* Hmm, we cannot increase the watermark any further, hence let's raise the latency */
+    /* Hmm, we cannot increase the watermark any further, hence let's
+     raise the latency unless doing so was disabled in
+     configuration */
+    if (u->fixed_latency_range)
+        return;
+
     old_min_latency = u->source->thread_info.min_latency;
     new_min_latency = PA_MIN(old_min_latency * 2, old_min_latency + TSCHED_WATERMARK_INC_STEP_USEC);
     new_min_latency = PA_MIN(new_min_latency, u->source->thread_info.max_latency);
@@ -1710,7 +1715,7 @@ pa_source *pa_alsa_source_new(pa_module *m, pa_modargs *ma, const char*driver, p
     uint32_t nfrags, frag_size, buffer_size, tsched_size, tsched_watermark;
     snd_pcm_uframes_t period_frames, buffer_frames, tsched_frames;
     size_t frame_size;
-    pa_bool_t use_mmap = TRUE, b, use_tsched = TRUE, d, ignore_dB = FALSE, namereg_fail = FALSE, deferred_volume = FALSE;
+    pa_bool_t use_mmap = TRUE, b, use_tsched = TRUE, d, ignore_dB = FALSE, namereg_fail = FALSE, deferred_volume = FALSE, fixed_latency_range = FALSE;
     pa_source_new_data data;
     pa_alsa_profile_set *profile_set = NULL;
 
@@ -1774,6 +1779,11 @@ pa_source *pa_alsa_source_new(pa_module *m, pa_modargs *ma, const char*driver, p
         goto fail;
     }
 
+    if (pa_modargs_get_value_boolean(ma, "fixed_latency_range", &fixed_latency_range) < 0) {
+        pa_log("Failed to parse fixed_latency_range argument.");
+        goto fail;
+    }
+
     use_tsched = pa_alsa_may_tsched(use_tsched);
 
     u = pa_xnew0(struct userdata, 1);
@@ -1782,6 +1792,7 @@ pa_source *pa_alsa_source_new(pa_module *m, pa_modargs *ma, const char*driver, p
     u->use_mmap = use_mmap;
     u->use_tsched = use_tsched;
     u->deferred_volume = deferred_volume;
+    u->fixed_latency_range = fixed_latency_range;
     u->first = TRUE;
     u->rtpoll = pa_rtpoll_new();
     pa_thread_mq_init(&u->thread_mq, m->core->mainloop, u->rtpoll);
@@ -1877,8 +1888,11 @@ pa_source *pa_alsa_source_new(pa_module *m, pa_modargs *ma, const char*driver, p
     if (u->use_mmap)
         pa_log_info("Successfully enabled mmap() mode.");
 
-    if (u->use_tsched)
+    if (u->use_tsched) {
         pa_log_info("Successfully enabled timer-based scheduling mode.");
+        if (u->fixed_latency_range)
+            pa_log_info("Disabling latency range changes on overrun");
+    }
 
     u->rates = pa_alsa_get_supported_rates(u->pcm_handle);
     if (!u->rates) {

diff --git a/src/modules/alsa/module-alsa-sink.c b/src/modules/alsa/module-alsa-sink.c
index 019ccf0eb0c16819f7c003ce79ef30ad0ff0e3ea..927f075ac659c6d0593b1282223807f017c35c4d 100644 (file)
--- a/src/modules/alsa/module-alsa-sink.c
+++ b/src/modules/alsa/module-alsa-sink.c
@@ -59,7 +59,8 @@ PA_MODULE_USAGE(
         "rewind_safeguard=<number of bytes that cannot be rewound> "
         "deferred_volume=<Synchronize software and hardware volume changes to avoid momentary jumps?> "
         "deferred_volume_safety_margin=<usec adjustment depending on volume direction> "
-        "deferred_volume_extra_delay=<usec adjustment to HW volume changes>");
+        "deferred_volume_extra_delay=<usec adjustment to HW volume changes> "
+        "fixed_latency_range=<disable latency range changes on underrun?>");
 
 static const char* const valid_modargs[] = {
     "name",
@@ -85,6 +86,7 @@ static const char* const valid_modargs[] = {
     "deferred_volume",
     "deferred_volume_safety_margin",
     "deferred_volume_extra_delay",
+    "fixed_latency_range",
     NULL
 };
 

diff --git a/src/modules/alsa/module-alsa-source.c b/src/modules/alsa/module-alsa-source.c
index 2d2c8b6492a3654a6a6ee8b9eeb8b1216d13fe1c..efb2d0c53eaf828502aac4ce93c01ccb0dfe07d5 100644 (file)
--- a/src/modules/alsa/module-alsa-source.c
+++ b/src/modules/alsa/module-alsa-source.c
@@ -67,7 +67,8 @@ PA_MODULE_USAGE(
         "control=<name of mixer control>"
         "deferred_volume=<Synchronize software and hardware volume changes to avoid momentary jumps?> "
         "deferred_volume_safety_margin=<usec adjustment depending on volume direction> "
-        "deferred_volume_extra_delay=<usec adjustment to HW volume changes>");
+        "deferred_volume_extra_delay=<usec adjustment to HW volume changes> "
+        "fixed_latency_range=<disable latency range changes on overrun?>");
 
 static const char* const valid_modargs[] = {
     "name",
@@ -92,6 +93,7 @@ static const char* const valid_modargs[] = {
     "deferred_volume",
     "deferred_volume_safety_margin",
     "deferred_volume_extra_delay",
+    "fixed_latency_range",
     NULL
 };
 

diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index 0ee4ead2135da003acb19655b5b739fafb7633af..d6bff11191b7dbdbd99a93f446596c13cfd0a57e 100644 (file)
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -1008,6 +1008,10 @@ static void fix_playback_buffer_attr(playback_stream *s) {
             tlength_usec -= s->configured_sink_latency;
     }
 
+    pa_log_debug("Requested latency=%0.2f ms, Received latency=%0.2f ms",
+                 (double) sink_usec / PA_USEC_PER_MSEC,
+                 (double) s->configured_sink_latency / PA_USEC_PER_MSEC);
+
     /* FIXME: This is actually larger than necessary, since not all of
      * the sink latency is actually rewritable. */
     if (tlength_usec < s->configured_sink_latency + 2*minreq_usec)