ALSA: Enable PCM hw_ptr_jiffies check only in xrun_debug mode
The PCM hw_ptr jiffies check results sometimes in problems when a
hardware doesn't give smooth hw_ptr updates. So far, au88x0 and some
other drivers appear not working due to this strict check.
However, this check is a nice debug tool, and the capability should be
still kept.
Hence, we disable this check now as default unless the user enables it
by setting the xrun_debug mode to the specific stream via a proc file.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/Documentation/sound/alsa/Procfile.txt b/Documentation/sound/alsa/Procfile.txt
index bba2dbb..cfac20c 100644
--- a/Documentation/sound/alsa/Procfile.txt
+++ b/Documentation/sound/alsa/Procfile.txt
@@ -104,6 +104,11 @@
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 3eea98a..d659995 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -249,6 +249,11 @@
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 @@
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",