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authorClemens Ladisch <clemens@ladisch.de>2010-11-15 10:46:23 +0100
committerTakashi Iwai <tiwai@suse.de>2010-11-22 08:13:16 +0100
commitab69a4904b5dd4d7cd6996587ba066bca8d13838 (patch)
tree8d51c631f1bd0bb72b9b528aa065ec9c0f4d0600 /sound/core/pcm_native.c
parentd2b88e4c103f37584dc81ef8a41ca584c1ce847b (diff)
downloadlinux-ab69a4904b5dd4d7cd6996587ba066bca8d13838.tar.bz2
ALSA: pcm: support for period wakeup disabling
This patch allows to disable period interrupts which are not needed when the application relies on a system timer to wake-up and refill the ring buffer. The behavior of the driver is left unchanged, and interrupts are only disabled if the application requests this configuration. The behavior in case of underruns is slightly different, instead of being detected during the period interrupts the underruns are detected when the application calls snd_pcm_update_avail, which in turns forces a refresh of the hw pointer and shows the buffer is empty. More specifically this patch makes a lot of sense when PulseAudio relies on timer-based scheduling to access audio devices such as HDAudio or Intel SST. Disabling interrupts removes two unwanted wake-ups due to period elapsed events in low-power playback modes. It also simplifies PulseAudio voice modules used for speech calls. To quote Lennart "This patch looks very interesting and desirable. This is something have long been waiting for." Support for this in hardware drivers is optional. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@intel.com> Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core/pcm_native.c')
-rw-r--r--sound/core/pcm_native.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 8bc7cb3db330..f91a439f675c 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -423,6 +423,9 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
runtime->info = params->info;
runtime->rate_num = params->rate_num;
runtime->rate_den = params->rate_den;
+ runtime->no_period_wakeup =
+ (params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) &&
+ (params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP);
bits = snd_pcm_format_physical_width(runtime->format);
runtime->sample_bits = bits;