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ALSA: aloop: using raw cycles and jiffies

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The system tick may be modified by NTP when we connect
with network, then  jiffies have an offset compared to
the local clock, it will cause the irq_pos / delta_play /
delta_capt also be inaccurate.

Therefore, we need a way to get raw jiffies which follows
local raw clocks.

Change-Id: I9be1790dfd98e430982dad6f03b04532889279a6
Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
This commit is contained in:
Xing Zheng
2018-10-23 16:23:32 +08:00
committed by Tao Huang
parent 90c8a9abbc
commit abbf433e4c
1 changed files with 24 additions and 5 deletions
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29
sound/drivers/aloop.c
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@@ -50,12 +50,15 @@ MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
#define MAX_PCM_SUBSTREAMS 8
static bool use_raw_jiffies;
static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-MAX */
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* ID for this card */
static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
static int pcm_notify[SNDRV_CARDS];
module_param(use_raw_jiffies, bool, 0444);
MODULE_PARM_DESC(use_raw_jiffies, "Use raw jiffies follows local clocks.");
module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
module_param_array(id, charp, NULL, 0444);
@@ -125,6 +128,22 @@ struct loopback_pcm {
static struct platform_device *devices[SNDRV_CARDS];
static inline unsigned long get_raw_jiffies(void)
{
struct timespec64 ts64;
getrawmonotonic64(&ts64);
return timespec64_to_jiffies(&ts64);
}
static inline unsigned long cycles_to_jiffies(void)
{
if (likely(use_raw_jiffies))
return get_raw_jiffies();
return jiffies;
}
static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
{
if (dpcm->pcm_rate_shift == NO_PITCH) {
@@ -270,7 +289,7 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
err = loopback_check_format(cable, substream->stream);
if (err < 0)
return err;
dpcm->last_jiffies = jiffies;
dpcm->last_jiffies = cycles_to_jiffies();
dpcm->pcm_rate_shift = 0;
dpcm->last_drift = 0;
spin_lock(&cable->lock);
@@ -302,7 +321,7 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
case SNDRV_PCM_TRIGGER_RESUME:
spin_lock(&cable->lock);
dpcm->last_jiffies = jiffies;
dpcm->last_jiffies = cycles_to_jiffies();
cable->pause &= ~stream;
loopback_timer_start(dpcm);
spin_unlock(&cable->lock);
@@ -482,12 +501,12 @@ static unsigned int loopback_pos_update(struct loopback_cable *cable)
running = cable->running ^ cable->pause;
if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
delta_play = jiffies - dpcm_play->last_jiffies;
delta_play = cycles_to_jiffies() - dpcm_play->last_jiffies;
dpcm_play->last_jiffies += delta_play;
}
if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
delta_capt = jiffies - dpcm_capt->last_jiffies;
delta_capt = cycles_to_jiffies() - dpcm_capt->last_jiffies;
dpcm_capt->last_jiffies += delta_capt;
}
@@ -1108,7 +1127,7 @@ static void print_dpcm_info(struct snd_info_buffer *buffer,
snd_iprintf(buffer, " irq_pos:\t\t%u\n", dpcm->irq_pos);
snd_iprintf(buffer, " period_frac:\t%u\n", dpcm->period_size_frac);
snd_iprintf(buffer, " last_jiffies:\t%lu (%lu)\n",
dpcm->last_jiffies, jiffies);
dpcm->last_jiffies, cycles_to_jiffies());
snd_iprintf(buffer, " timer_expires:\t%lu\n", dpcm->timer.expires);
}