ALSA: dummy - Fix the timer calculation in systimer mode

Fix the expire-time calculation in the systimer mode when the buffer
size isn't aligned to the period size.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 21 insertions, 8 deletions

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index 0a798bde0d03..e8e29bfb85ec 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -207,19 +207,18 @@ struct dummy_systimer_pcm {
         struct timer_list timer;
         unsigned long base_time;
         unsigned int frac_pos;  /* fractional sample position (based HZ) */
+        unsigned int frac_period_rest;
         unsigned int frac_buffer_size;  /* buffer_size * HZ */
         unsigned int frac_period_size;  /* period_size * HZ */
         unsigned int rate;
+        int elapsed;
         struct snd_pcm_substream *substream;
 };
 
 static void dummy_systimer_rearm(struct dummy_systimer_pcm *dpcm)
 {
-        unsigned long frac;
-
-        frac = dpcm->frac_pos % dpcm->frac_period_size;
         dpcm->timer.expires = jiffies +
-                (dpcm->frac_period_size + dpcm->rate - 1) / dpcm->rate;
+                (dpcm->frac_period_rest + dpcm->rate - 1) / dpcm->rate;
         add_timer(&dpcm->timer);
 }
 
@@ -230,10 +229,16 @@ static void dummy_systimer_update(struct dummy_systimer_pcm *dpcm)
         delta = jiffies - dpcm->base_time;
         if (!delta)
                 return;
-        dpcm->base_time = jiffies;
-        dpcm->frac_pos += delta * dpcm->rate;
+        dpcm->base_time += delta;
+        delta *= dpcm->rate;
+        dpcm->frac_pos += delta;
         while (dpcm->frac_pos >= dpcm->frac_buffer_size)
                 dpcm->frac_pos -= dpcm->frac_buffer_size;
+        while (dpcm->frac_period_rest <= delta) {
+                dpcm->elapsed++;
+                dpcm->frac_period_rest += dpcm->frac_period_size;
+        }
+        dpcm->frac_period_rest -= delta;
 }
 
 static int dummy_systimer_start(struct snd_pcm_substream *substream)
@@ -264,6 +269,8 @@ static int dummy_systimer_prepare(struct snd_pcm_substream *substream)
         dpcm->rate = runtime->rate;
         dpcm->frac_buffer_size = runtime->buffer_size * HZ;
         dpcm->frac_period_size = runtime->period_size * HZ;
+        dpcm->frac_period_rest = dpcm->frac_period_size;
+        dpcm->elapsed = 0;
 
         return 0;
 }
@@ -272,23 +279,29 @@ static void dummy_systimer_callback(unsigned long data)
 {
         struct dummy_systimer_pcm *dpcm = (struct dummy_systimer_pcm *)data;
         unsigned long flags;
+        int elapsed = 0;
         
         spin_lock_irqsave(&dpcm->lock, flags);
         dummy_systimer_update(dpcm);
         dummy_systimer_rearm(dpcm);
+        elapsed = dpcm->elapsed;
+        dpcm->elapsed = 0;
         spin_unlock_irqrestore(&dpcm->lock, flags);
-        snd_pcm_period_elapsed(dpcm->substream);
+        if (elapsed)
+                snd_pcm_period_elapsed(dpcm->substream);
 }
 
 static snd_pcm_uframes_t
 dummy_systimer_pointer(struct snd_pcm_substream *substream)
 {
         struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+        snd_pcm_uframes_t pos;
 
         spin_lock(&dpcm->lock);
         dummy_systimer_update(dpcm);
+        pos = dpcm->frac_pos / HZ;
         spin_unlock(&dpcm->lock);
-        return dpcm->frac_pos / HZ;
+        return pos;
 }
 
 static int dummy_systimer_create(struct snd_pcm_substream *substream)