ALSA: ctxfi - Optimize the native timer handling using wc counter

Optimize the timer update routine to look up wall clock once instead of
checking the position of each stream at each timer update.

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

1 files changed, 48 insertions, 28 deletions

diff --git a/sound/pci/ctxfi/cttimer.c b/sound/pci/ctxfi/cttimer.c
index ceda74e..ec869a4 100644
--- a/sound/pci/ctxfi/cttimer.c
+++ b/sound/pci/ctxfi/cttimer.c
@@ -47,6 +47,7 @@ struct ct_timer {
 	struct ct_timer_ops *ops;
 	struct list_head instance_head;
 	struct list_head running_head;
+	unsigned int wc;		/* current wallclock */
 	unsigned int irq_handling:1;	/* in IRQ handling */
 	unsigned int reprogram:1;	/* need to reprogram the internval */
 	unsigned int running:1;		/* global timer running */
@@ -136,6 +137,7 @@ static struct ct_timer_ops ct_systimer_ops = {
  */
 
 #define CT_TIMER_FREQ	48000
+#define MIN_TICKS	1
 #define MAX_TICKS	((1 << 13) - 1)
 
 static void ct_xfitimer_irq_rearm(struct ct_timer *atimer, int ticks)
@@ -159,6 +161,12 @@ static void ct_xfitimer_irq_stop(struct ct_timer *atimer)
 	}
 }
 
+static inline unsigned int ct_xfitimer_get_wc(struct ct_timer *atimer)
+{
+	struct hw *hw = atimer->atc->hw;
+	return hw->get_wc(hw);
+}
+
 /*
  * reprogram the timer interval;
  * checks the running instance list and determines the next timer interval.
@@ -170,37 +178,46 @@ static void ct_xfitimer_irq_stop(struct ct_timer *atimer)
 static int ct_xfitimer_reprogram(struct ct_timer *atimer)
 {
 	struct ct_timer_instance *ti;
-	int min_intr = -1;
+	unsigned int min_intr = (unsigned int)-1;
 	int updates = 0;
+	unsigned int wc, diff;
 
+	if (list_empty(&atimer->running_head)) {
+		ct_xfitimer_irq_stop(atimer);
+		atimer->reprogram = 0; /* clear flag */
+		return 0;
+	}
+
+	wc = ct_xfitimer_get_wc(atimer);
+	diff = wc - atimer->wc;
+	atimer->wc = wc;
 	list_for_each_entry(ti, &atimer->running_head, running_list) {
-		struct snd_pcm_runtime *runtime;
-		unsigned int pos, diff;
-		int intr;
-		runtime = ti->substream->runtime;
-		pos = ti->substream->ops->pointer(ti->substream);
-		if (pos < ti->position)
-			diff = runtime->buffer_size - ti->position + pos;
-		else
-			diff = pos - ti->position;
-		ti->position = pos;
-		while (diff >= ti->frag_count) {
-			ti->frag_count += runtime->period_size;
-			ti->need_update = 1;
-			updates++;
+		if (ti->frag_count > diff)
+			ti->frag_count -= diff;
+		else {
+			unsigned int pos;
+			unsigned int period_size, rate;
+
+			period_size = ti->substream->runtime->period_size;
+			rate = ti->substream->runtime->rate;
+			pos = ti->substream->ops->pointer(ti->substream);
+			if (pos / period_size != ti->position / period_size) {
+				ti->need_update = 1;
+				ti->position = pos;
+				updates++;
+			}
+			pos %= period_size;
+			pos = period_size - pos;
+			ti->frag_count = div_u64((u64)pos * CT_TIMER_FREQ +
+						 rate - 1, rate);
 		}
-		ti->frag_count -= diff;
-		intr = div_u64((u64)ti->frag_count * CT_TIMER_FREQ,
-			       runtime->rate);
-		if (min_intr < 0 || intr < min_intr)
-			min_intr = intr;
+		if (ti->frag_count < min_intr)
+			min_intr = ti->frag_count;
 	}
 
-	if (min_intr > 0)
-		ct_xfitimer_irq_rearm(atimer, min_intr);
-	else
-		ct_xfitimer_irq_stop(atimer);
-
+	if (min_intr < MIN_TICKS)
+		min_intr = MIN_TICKS;
+	ct_xfitimer_irq_rearm(atimer, min_intr);
 	atimer->reprogram = 0; /* clear flag */
 	return updates;
 }
@@ -253,13 +270,14 @@ static void ct_xfitimer_update(struct ct_timer *atimer)
 	unsigned long flags;
 	int update;
 
+	spin_lock_irqsave(&atimer->lock, flags);
 	if (atimer->irq_handling) {
 		/* reached from IRQ handler; let it handle later */
 		atimer->reprogram = 1;
+		spin_unlock_irqrestore(&atimer->lock, flags);
 		return;
 	}
 
-	spin_lock_irqsave(&atimer->lock, flags);
 	ct_xfitimer_irq_stop(atimer);
 	update = ct_xfitimer_reprogram(atimer);
 	spin_unlock_irqrestore(&atimer->lock, flags);
@@ -273,6 +291,8 @@ static void ct_xfitimer_start(struct ct_timer_instance *ti)
 	unsigned long flags;
 
 	spin_lock_irqsave(&atimer->lock, flags);
+	if (list_empty(&ti->running_list))
+		atimer->wc = ct_xfitimer_get_wc(atimer);
 	list_add(&ti->running_list, &atimer->running_head);
 	spin_unlock_irqrestore(&atimer->lock, flags);
 	ct_xfitimer_update(atimer);
@@ -396,12 +416,12 @@ struct ct_timer *ct_timer_new(struct ct_atc *atc)
 	atimer->atc = atc;
 	hw = atc->hw;
 	if (!USE_SYSTEM_TIMER && hw->set_timer_irq) {
-		printk(KERN_INFO "ctxfi: Use xfi-native timer\n");
+		snd_printd(KERN_INFO "ctxfi: Use xfi-native timer\n");
 		atimer->ops = &ct_xfitimer_ops;
 		hw->irq_callback_data = atimer;
 		hw->irq_callback = ct_timer_interrupt;
 	} else {
-		printk(KERN_INFO "ctxfi: Use system timer\n");
+		snd_printd(KERN_INFO "ctxfi: Use system timer\n");
 		atimer->ops = &ct_systimer_ops;
 	}
 	return atimer;