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Commit c87d9732 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

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: default avatarTakashi Iwai <tiwai@suse.de>
parent 6af3fb72

Documentation/sound/alsa/Procfile.txt

+5 −0
Original line number Diff line number Diff line
@@ -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.

sound/core/pcm_lib.c

+8 −1
Original line number Diff line number Diff line
@@ -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",