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alsa: disable period wakeups in tsched mode if possible

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This patch reflects a new capability that Lennart was wishing
for. Wish granted...

Re-submitting it now that alsa-lib 1.0.24
provides additional entry points to disable period
wakeups in timer-scheduling mode if hardware can
work without it (HDAudio, oxygen and Intel SST).

    Example with standard playback on HDAudio output
    Before change:

    Top causes for wakeups:
       3.8% (  5.4)   [hda_intel] <interrupt>
       2.8% (  4.0)   alsa-sink

    After change:
    Top causes for wakeups:
       2.3% (  3.0)   alsa-sink

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@intel.com>
This commit is contained in:
Pierre-Louis Bossart 2011-01-31 13:20:27 -06:00 • committed by Colin Guthrie
parent 9498440dc6
commit 051d82133f
1 changed files with 28 additions and 0 deletions
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28
src/modules/alsa/alsa-util.c
View file

@ -251,6 +251,22 @@ int pa_alsa_set_hw_params(
if (!pa_alsa_pcm_is_hw(pcm_handle)) if (!pa_alsa_pcm_is_hw(pcm_handle))
_use_tsched = FALSE; _use_tsched = FALSE;
#if (SND_LIB_VERSION >= ((1<<16)|(0<<8)|24)) /* API additions in 1.0.24 */
if (_use_tsched) {
/* try to disable period wakeups if hardware can do so */
if (snd_pcm_hw_params_can_disable_period_wakeup(hwparams)) {
if (snd_pcm_hw_params_set_period_wakeup(pcm_handle, hwparams, FALSE) < 0)
/* don't bail, keep going with default mode with period wakeups */
pa_log_debug("snd_pcm_hw_params_set_period_wakeup() failed: %s", pa_alsa_strerror(ret));
else
pa_log_info("Trying to disable ALSA period wakeups, using timers only");
} else
pa_log_info("cannot disable ALSA period wakeups");
}
#endif
if ((ret = set_format(pcm_handle, hwparams, &_ss.format)) < 0) if ((ret = set_format(pcm_handle, hwparams, &_ss.format)) < 0)
goto finish; goto finish;
@ -378,6 +394,18 @@ success:
goto finish; goto finish;
} }
#if (SND_LIB_VERSION >= ((1<<16)|(0<<8)|24)) /* API additions in 1.0.24 */
if (_use_tsched) {
unsigned int no_wakeup;
/* see if period wakeups were disabled */
snd_pcm_hw_params_get_period_wakeup(pcm_handle, hwparams, &no_wakeup);
if (no_wakeup == 0)
pa_log_info("ALSA period wakeups disabled");
else
pa_log_info("ALSA period wakeups were not disabled");
}
#endif
ss->rate = _ss.rate; ss->rate = _ss.rate;
ss->channels = _ss.channels; ss->channels = _ss.channels;
ss->format = _ss.format; ss->format = _ss.format;