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-rw-r--r--Documentation/sound/alsa/Procfile.txt5
-rw-r--r--sound/core/pcm_lib.c9
2 files changed, 13 insertions, 1 deletions
diff --git a/Documentation/sound/alsa/Procfile.txt b/Documentation/sound/alsa/Procfile.txt
index bba2dbb79d8..cfac20cf9e3 100644
--- a/Documentation/sound/alsa/Procfile.txt
+++ b/Documentation/sound/alsa/Procfile.txt
@@ -104,6 +104,11 @@ card*/pcm*/xrun_debug
When this value is greater than 1, the driver will show the
stack trace additionally. This may help the debugging.
+ Since 2.6.30, this option also enables the hwptr check using
+ jiffies. This detects spontaneous invalid pointer callback
+ values, but can be lead to too much corrections for a (mostly
+ buggy) hardware that doesn't give smooth pointer updates.
+
card*/pcm*/sub*/info
The general information of this PCM sub-stream.
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 3eea98a4e65..d659995ac3a 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -249,6 +249,11 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
new_hw_ptr = hw_base + pos;
}
}
+
+ /* Do jiffies check only in xrun_debug mode */
+ if (!xrun_debug(substream))
+ goto no_jiffies_check;
+
/* Skip the jiffies check for hardwares with BATCH flag.
* Such hardware usually just increases the position at each IRQ,
* thus it can't give any strange position.
@@ -336,7 +341,9 @@ int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream)
hw_base = 0;
new_hw_ptr = hw_base + pos;
}
- if (((delta * HZ) / runtime->rate) > jdelta + HZ/100) {
+ /* Do jiffies check only in xrun_debug mode */
+ if (xrun_debug(substream) &&
+ ((delta * HZ) / runtime->rate) > jdelta + HZ/100) {
hw_ptr_error(substream,
"hw_ptr skipping! "
"(pos=%ld, delta=%ld, period=%ld, jdelta=%lu/%lu)\n",