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pcm: hw: introduce SNDRV_PCM_INFO_PERFECT_DRAIN

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Handle the driver informing us that it is not necessary to set up
silencing upon playback draining. This will be the case for drivers
which are guaranteed to not read any samples beyond the application
pointer.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2023-04-25 14:36:19 +02:00
parent dd9cb31a90
commit 90e25887d2
5 changed files with 30 additions and 1 deletions
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1
include/pcm.h
View file

@ -722,6 +722,7 @@ int snd_pcm_hw_params_is_half_duplex(const snd_pcm_hw_params_t *params);
int snd_pcm_hw_params_is_joint_duplex(const snd_pcm_hw_params_t *params);
int snd_pcm_hw_params_can_sync_start(const snd_pcm_hw_params_t *params);
int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *params);
int snd_pcm_hw_params_is_perfect_drain(const snd_pcm_hw_params_t *params);
int snd_pcm_hw_params_supports_audio_wallclock_ts(const snd_pcm_hw_params_t *params); /* deprecated, use audio_ts_type */
int snd_pcm_hw_params_supports_audio_ts_type(const snd_pcm_hw_params_t *params, int type);
int snd_pcm_hw_params_get_rate_numden(const snd_pcm_hw_params_t *params,

1
include/sound/uapi/asound.h
View file

@ -281,6 +281,7 @@ typedef int __bitwise snd_pcm_subformat_t;
#define SNDRV_PCM_INFO_DOUBLE 0x00000004 /* Double buffering needed for PCM start/stop */
#define SNDRV_PCM_INFO_BATCH 0x00000010 /* double buffering */
#define SNDRV_PCM_INFO_SYNC_APPLPTR 0x00000020 /* need the explicit sync of appl_ptr update */
#define SNDRV_PCM_INFO_PERFECT_DRAIN 0x00000040 /* silencing at the end of stream is not required */
#define SNDRV_PCM_INFO_INTERLEAVED 0x00000100 /* channels are interleaved */
#define SNDRV_PCM_INFO_NONINTERLEAVED 0x00000200 /* channels are not interleaved */
#define SNDRV_PCM_INFO_COMPLEX 0x00000400 /* complex frame organization (mmap only) */

23
src/pcm/pcm.c
View file

@ -3707,6 +3707,29 @@ int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *param
return !!(params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP);
}
/**
* \brief Check if hardware is capable of perfect drain
* \param params Configuration space
* \retval 0 Hardware doesn't do perfect drain
* \retval 1 Hardware does perfect drain
*
* This function should only be called when the configuration space
* contains a single configuration. Call #snd_pcm_hw_params to choose
* a single configuration from the configuration space.
*
* Perfect drain means that the hardware does not use samples
* beyond the stream application pointer.
*/
int snd_pcm_hw_params_is_perfect_drain(const snd_pcm_hw_params_t *params)
{
assert(params);
if (CHECK_SANITY(params->info == ~0U)) {
SNDMSG("invalid PCM info field");
return 0; /* FIXME: should be a negative error? */
}
return !!(params->info & SNDRV_PCM_INFO_PERFECT_DRAIN);
}
/**
* \brief Check if hardware supports audio wallclock timestamps
* \param params Configuration space

4
src/pcm/pcm_hw.c
View file

@ -99,6 +99,7 @@ typedef struct {
struct snd_pcm_sync_ptr *sync_ptr;
bool prepare_reset_sw_params;
bool perfect_drain;
int period_event;
snd_timer_t *period_timer;
@ -398,6 +399,7 @@ static int snd_pcm_hw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
params->info &= ~0xf0000000;
if (pcm->tstamp_type != SND_PCM_TSTAMP_TYPE_GETTIMEOFDAY)
params->info |= SND_PCM_INFO_MONOTONIC;
hw->perfect_drain = !!(params->info & SND_PCM_INFO_PERFECT_DRAIN);
return query_status_data(hw);
}
@ -739,7 +741,7 @@ static int snd_pcm_hw_drain(snd_pcm_t *pcm)
if (pcm->stream != SND_PCM_STREAM_PLAYBACK)
goto __skip_silence;
if (hw->drain_silence == 0)
if (hw->drain_silence == 0 || hw->perfect_drain)
goto __skip_silence;
snd_pcm_sw_params_current_no_lock(pcm, &sw_params);
if (hw->drain_silence > 0) {

2
src/pcm/pcm_local.h
View file

@ -79,6 +79,8 @@
#define SND_PCM_INFO_DOUBLE SNDRV_PCM_INFO_DOUBLE
/** device transfers samples in batch */
#define SND_PCM_INFO_BATCH SNDRV_PCM_INFO_BATCH
/** device does perfect drain (silencing not required) */
#define SND_PCM_INFO_PERFECT_DRAIN SNDRV_PCM_INFO_PERFECT_DRAIN
/** device accepts interleaved samples */
#define SND_PCM_INFO_INTERLEAVED SNDRV_PCM_INFO_INTERLEAVED
/** device accepts non-interleaved samples */