AOSP CL "pcm: add support to set silence_size"

https://android.googlesource.com/platform/external/tinyalsa/+/e25fe0b50ea717a9f347dcb927d396e8772e6362

commit	e25fe0b50ea717a9f347dcb927d396e8772e6362
author	Maneet Singh <mmaneetsingh@nvidia.com>

pcm: add support to set silence_size

Tinyalsa always set silence_size to zero. Add support to set this
pcm software parameter as required.

Bug: 20226809
Bug: 20300203
Change-Id: I25de43623dc04bf5a3ad4c6573bc2b8dad1eec5e

2 files changed, 10 insertions, 4 deletions

diff --git a/include/tinyalsa/pcm.h b/include/tinyalsa/pcm.h
index 5191882..f32e11d 100644
--- a/include/tinyalsa/pcm.h
+++ b/include/tinyalsa/pcm.h
@@ -202,13 +202,15 @@ struct pcm_config {
     unsigned int period_count;
     /** The sample format of a PCM */
     enum pcm_format format;
-    /* Values to use for the ALSA start, stop and silence thresholds.  Setting
-     * any one of these values to 0 will cause the default tinyalsa values to be
-     * used instead.  Tinyalsa defaults are as follows.
+    /* Values to use for the ALSA start, stop and silence thresholds, and
+     * silence size.  Setting any one of these values to 0 will cause the
+     * default tinyalsa values to be used instead.
+     * Tinyalsa defaults are as follows.
      *
      * start_threshold   : period_count * period_size
      * stop_threshold    : period_count * period_size
      * silence_threshold : 0
+     * silence_size      : 0
      */
     /** The minimum number of frames required to start the PCM */
     unsigned int start_threshold;
@@ -216,6 +218,9 @@ struct pcm_config {
     unsigned int stop_threshold;
     /** The minimum number of frames to silence the PCM */
     unsigned int silence_threshold;
+    /** The number of frames to overwrite the playback buffer when the playback underrun is greater
+     * than the silence threshold */
+    unsigned int silence_size;
 };
 
 /** Enumeration of a PCM's hardware parameters.
diff --git a/src/pcm.c b/src/pcm.c
index 406ac8d..8da3241 100644
--- a/src/pcm.c
+++ b/src/pcm.c
@@ -438,6 +438,7 @@ int pcm_set_config(struct pcm *pcm, const struct pcm_config *config)
         pcm->config.start_threshold = config->period_count * config->period_size;
         pcm->config.stop_threshold = config->period_count * config->period_size;
         pcm->config.silence_threshold = 0;
+        pcm->config.silence_size = 0;
     } else
         pcm->config = *config;
 
@@ -519,7 +520,7 @@ int pcm_set_config(struct pcm *pcm, const struct pcm_config *config)
         sparams.stop_threshold = config->stop_threshold;
 
     sparams.xfer_align = config->period_size / 2; /* needed for old kernels */
-    sparams.silence_size = 0;
+    sparams.silence_size = config->silence_size;
     sparams.silence_threshold = config->silence_threshold;
     pcm->boundary = sparams.boundary = pcm->buffer_size;