ubuntu-audio-dev team mailing list archive

[Daniel Chen <seven.steps@xxxxxxxxx>]

The patch referenced here is *highly* useful:

http://mailman.alsa-project.org/pipermail/alsa-devel/2010-May/027557.html

Namely, we can eliminate a large class of bug reports by applying it
to Lucid. This is changeset 432f57d10 in alsa-kernel.git.

Best,
-Dan

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index cad9b70..0a6c55b 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -174,7 +174,7 @@ MODULE_DESCRIPTION("Intel HDA driver");
 #define   ICH6_GSTS_FSTS	(1 << 1)   /* flush status */
 #define ICH6_REG_INTCTL			0x20
 #define ICH6_REG_INTSTS			0x24
-#define ICH6_REG_WALCLK			0x30
+#define ICH6_REG_WALLCLK		0x30	/* 24Mhz source */
 #define ICH6_REG_SYNC			0x34	
 #define ICH6_REG_CORBLBASE		0x40
 #define ICH6_REG_CORBUBASE		0x44
@@ -340,8 +340,8 @@ struct azx_dev {
 	unsigned int period_bytes; /* size of the period in bytes */
 	unsigned int frags;	/* number for period in the play buffer */
 	unsigned int fifo_size;	/* FIFO size */
-	unsigned long start_jiffies;	/* start + minimum jiffies */
-	unsigned long min_jiffies;	/* minimum jiffies before position is valid */
+	unsigned long start_wallclk;	/* start + minimum wallclk */
+	unsigned long period_wallclk;	/* wallclk for period */
 
 	void __iomem *sd_addr;	/* stream descriptor pointer */
 
@@ -361,7 +361,6 @@ struct azx_dev {
 	unsigned int opened :1;
 	unsigned int running :1;
 	unsigned int irq_pending :1;
-	unsigned int start_flag: 1;	/* stream full start flag */
 	/*
 	 * For VIA:
 	 *  A flag to ensure DMA position is 0
@@ -1676,8 +1675,9 @@ static int azx_pcm_prepare(struct snd_pcm_substream *substream)
 			return err;
 	}
 
-	azx_dev->min_jiffies = (runtime->period_size * HZ) /
-						(runtime->rate * 2);
+	/* wallclk has 24Mhz clock source */
+	azx_dev->period_wallclk = (((runtime->period_size * 24000) /
+						runtime->rate) * 1000);
 	azx_setup_controller(chip, azx_dev);
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		azx_dev->fifo_size = azx_sd_readw(azx_dev, SD_FIFOSIZE) + 1;
@@ -1731,14 +1731,15 @@ static int azx_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 		if (s->pcm->card != substream->pcm->card)
 			continue;
 		azx_dev = get_azx_dev(s);
-		if (rstart) {
-			azx_dev->start_flag = 1;
-			azx_dev->start_jiffies = jiffies + azx_dev->min_jiffies;
-		}
-		if (start)
+		if (start) {
+			azx_dev->start_wallclk = azx_readl(chip, WALLCLK);
+			if (!rstart)
+				azx_dev->start_wallclk -=
+						azx_dev->period_wallclk;
 			azx_stream_start(chip, azx_dev);
-		else
+		} else {
 			azx_stream_stop(chip, azx_dev);
+		}
 		azx_dev->running = start;
 	}
 	spin_unlock(&chip->reg_lock);
@@ -1885,13 +1886,14 @@ static snd_pcm_uframes_t azx_pcm_pointer(struct snd_pcm_substream *substream)
  */
 static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
 {
+	u32 wallclk;
 	unsigned int pos;
 	int stream;
 
-	if (azx_dev->start_flag &&
-	    time_before_eq(jiffies, azx_dev->start_jiffies))
+	wallclk = azx_readl(chip, WALLCLK);
+	if ((wallclk - azx_dev->start_wallclk) <
+				(azx_dev->period_wallclk * 2) / 3)
 		return -1;	/* bogus (too early) interrupt */
-	azx_dev->start_flag = 0;
 
 	stream = azx_dev->substream->stream;
 	pos = azx_get_position(chip, azx_dev);
@@ -1906,13 +1908,12 @@ static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
 			chip->position_fix[stream] = POS_FIX_POSBUF;
 	}
 
-	if (!bdl_pos_adj[chip->dev_index])
-		return 1; /* no delayed ack */
 	if (WARN_ONCE(!azx_dev->period_bytes,
 		      "hda-intel: zero azx_dev->period_bytes"))
 		return 0; /* this shouldn't happen! */
 	if (pos % azx_dev->period_bytes > azx_dev->period_bytes / 2)
 		return 0; /* NG - it's below the period boundary */
+	azx_dev->start_wallclk = wallclk;
 	return 1; /* OK, it's fine */
 }
 
@@ -1922,7 +1923,7 @@ static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
 static void azx_irq_pending_work(struct work_struct *work)
 {
 	struct azx *chip = container_of(work, struct azx, irq_pending_work);
-	int i, pending;
+	int i, pending, ok;
 
 	if (!chip->irq_pending_warned) {
 		printk(KERN_WARNING
@@ -1941,11 +1942,14 @@ static void azx_irq_pending_work(struct work_struct *work)
 			    !azx_dev->substream ||
 			    !azx_dev->running)
 				continue;
-			if (azx_position_ok(chip, azx_dev)) {
+			ok = azx_position_ok(chip, azx_dev);
+			if (ok > 0) {
 				azx_dev->irq_pending = 0;
 				spin_unlock(&chip->reg_lock);
 				snd_pcm_period_elapsed(azx_dev->substream);
 				spin_lock(&chip->reg_lock);
+			} else if (ok < 0) {
+				pending = 0;	/* too early */
 			} else
 				pending++;
 		}