[pulseaudio-discuss] [PATCH] Fix unused buffer size to avoid xrun

[Feng Wei]

When set latency is less than period time, we will assgin working
buffer less than a period size, which will cause unnecessary xrun
and wrong message indicating alsa driver bug.

Signed-off-by: Feng Wei <feng.wei at linaro.org>
---
 src/modules/alsa/alsa-sink.c   |    6 +++---
 src/modules/alsa/alsa-source.c |    6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c
index 5a4b606..a53fb6f 100644
--- a/src/modules/alsa/alsa-sink.c
+++ b/src/modules/alsa/alsa-sink.c
@@ -953,10 +953,10 @@ static int update_sw_params(struct userdata *u) {
 
             b = pa_usec_to_bytes(latency, &u->sink->sample_spec);
 
-            /* We need at least one sample in our buffer */
+            /* We need at least one period and one sample in our buffer to avoid underflow */
 
-            if (PA_UNLIKELY(b < u->frame_size))
-                b = u->frame_size;
+            if (PA_UNLIKELY(b < u->frame_size + u->fragment_size))
+                b = u->frame_size + u->fragment_size;
 
             u->hwbuf_unused = PA_LIKELY(b < u->hwbuf_size) ? (u->hwbuf_size - b) : 0;
         }
diff --git a/src/modules/alsa/alsa-source.c b/src/modules/alsa/alsa-source.c
index 27fd3b9..8c41ca6 100644
--- a/src/modules/alsa/alsa-source.c
+++ b/src/modules/alsa/alsa-source.c
@@ -876,10 +876,10 @@ static int update_sw_params(struct userdata *u) {
 
             b = pa_usec_to_bytes(latency, &u->source->sample_spec);
 
-            /* We need at least one sample in our buffer */
+            /* We need at least one period and one sample in our buffer to avoid overflow */
 
-            if (PA_UNLIKELY(b < u->frame_size))
-                b = u->frame_size;
+            if (PA_UNLIKELY(b < u->frame_size + u->fragment_size))
+                b = u->frame_size + u->fragment_size;
 
             u->hwbuf_unused = PA_LIKELY(b < u->hwbuf_size) ? (u->hwbuf_size - b) : 0;
         }
-- 
1.7.4.1