path: root/include
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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 /include
parentMerge branch 'fix/misc' into topic/misc (diff)
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 'include')
2 files changed, 4 insertions, 0 deletions
diff --git a/include/sound/asound.h b/include/sound/asound.h
index a1803ecea34d..5d6074faa279 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -259,6 +259,7 @@ typedef int __bitwise snd_pcm_subformat_t;
#define SNDRV_PCM_INFO_HALF_DUPLEX 0x00100000 /* only half duplex */
#define SNDRV_PCM_INFO_JOINT_DUPLEX 0x00200000 /* playback and capture stream are somewhat correlated */
#define SNDRV_PCM_INFO_SYNC_START 0x00400000 /* pcm support some kind of sync go */
+#define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP 0x00800000 /* period wakeup can be disabled */
#define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */
typedef int __bitwise snd_pcm_state_t;
@@ -334,6 +335,8 @@ typedef int snd_pcm_hw_param_t;
#define SNDRV_PCM_HW_PARAMS_NORESAMPLE (1<<0) /* avoid rate resampling */
+#define SNDRV_PCM_HW_PARAMS_EXPORT_BUFFER (1<<1) /* export buffer */
+#define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2) /* disable period wakeups */
struct snd_interval {
unsigned int min, max;
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index dfd9b76b1853..e731f8d71934 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -297,6 +297,7 @@ struct snd_pcm_runtime {
unsigned int info;
unsigned int rate_num;
unsigned int rate_den;
+ unsigned int no_period_wakeup: 1;
/* -- SW params -- */
int tstamp_mode; /* mmap timestamp is updated */