[ALSA] snd-dummy - improved timing, silence on prepare

Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/drivers/dummy.c

@@ -181,10 +181,10 @@ struct snd_dummy_pcm {
 	struct snd_dummy *dummy;
 	spinlock_t lock;
 	struct timer_list timer;
-	unsigned int pcm_size;
-	unsigned int pcm_count;
+	unsigned int pcm_buffer_size;
+	unsigned int pcm_period_size;
 	unsigned int pcm_bps;		/* bytes per second */
-	unsigned int pcm_jiffie;	/* bytes per one jiffie */
+	unsigned int pcm_hz;		/* HZ */
 	unsigned int pcm_irq_pos;	/* IRQ position */
 	unsigned int pcm_buf_pos;	/* position in buffer */
 	struct snd_pcm_substream *substream;
@@ -238,11 +238,15 @@ static int snd_card_dummy_pcm_prepare(struct snd_pcm_substream *substream)
 	if (bps <= 0)
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
-	dpcm->pcm_jiffie = bps / HZ;
-	dpcm->pcm_size = snd_pcm_lib_buffer_bytes(substream);
-	dpcm->pcm_count = snd_pcm_lib_period_bytes(substream);
+	dpcm->pcm_hz = HZ;
+	dpcm->pcm_buffer_size = snd_pcm_lib_buffer_bytes(substream);
+	dpcm->pcm_period_size = snd_pcm_lib_period_bytes(substream);
 	dpcm->pcm_irq_pos = 0;
 	dpcm->pcm_buf_pos = 0;
+
+	snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+			bytes_to_samples(runtime, runtime->dma_bytes));
+
 	return 0;
 }
 
@@ -254,11 +258,11 @@ static void snd_card_dummy_pcm_timer_function(unsigned long data)
 	spin_lock_irqsave(&dpcm->lock, flags);
 	dpcm->timer.expires = 1 + jiffies;
 	add_timer(&dpcm->timer);
-	dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos %= dpcm->pcm_size;
-	if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
-		dpcm->pcm_irq_pos %= dpcm->pcm_count;
+	dpcm->pcm_irq_pos += dpcm->pcm_bps;
+	if (dpcm->pcm_irq_pos >= dpcm->pcm_period_size * dpcm->pcm_hz) {
+		dpcm->pcm_irq_pos %= dpcm->pcm_period_size * dpcm->pcm_hz;
+		dpcm->pcm_buf_pos += dpcm->pcm_period_size;
+		dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size;
 		spin_unlock_irqrestore(&dpcm->lock, flags);
 		snd_pcm_period_elapsed(dpcm->substream);
 	} else