int number;
char name[32]; /* substream name */
int stream; /* stream (direction) */
+ char latency_id[20]; /* latency identifier */
size_t buffer_bytes_max; /* limit ring buffer size */
struct snd_dma_buffer dma_buffer;
unsigned int dma_buf_id;
substream->number = idx;
substream->stream = stream;
sprintf(substream->name, "subdevice #%i", idx);
+ snprintf(substream->latency_id, sizeof(substream->latency_id),
+ "ALSA-PCM%d-%d%c%d", pcm->card->number, pcm->device,
+ (stream ? 'c' : 'p'), idx);
substream->buffer_bytes_max = UINT_MAX;
if (prev == NULL)
pstr->substream = substream;
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/time.h>
+#include <linux/latency.h>
#include <linux/uio.h>
#include <sound/core.h>
#include <sound/control.h>
return err;
}
+static int period_to_usecs(struct snd_pcm_runtime *runtime)
+{
+ int usecs;
+
+ if (! runtime->rate)
+ return -1; /* invalid */
+
+ /* take 75% of period time as the deadline */
+ usecs = (750000 / runtime->rate) * runtime->period_size;
+ usecs += ((750000 % runtime->rate) * runtime->period_size) /
+ runtime->rate;
+
+ return usecs;
+}
+
static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct snd_pcm_runtime *runtime;
- int err;
+ int err, usecs;
unsigned int bits;
snd_pcm_uframes_t frames;
snd_pcm_timer_resolution_change(substream);
runtime->status->state = SNDRV_PCM_STATE_SETUP;
+
+ remove_acceptable_latency(substream->latency_id);
+ if ((usecs = period_to_usecs(runtime)) >= 0)
+ set_acceptable_latency(substream->latency_id, usecs);
return 0;
_error:
/* hardware might be unuseable from this time,
if (substream->ops->hw_free)
result = substream->ops->hw_free(substream);
runtime->status->state = SNDRV_PCM_STATE_OPEN;
+ remove_acceptable_latency(substream->latency_id);
return result;
}