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-rw-r--r--sound/pci/es1968.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/sound/pci/es1968.c b/sound/pci/es1968.c
index 67f03264f871..f8f3bb662d17 100644
--- a/sound/pci/es1968.c
+++ b/sound/pci/es1968.c
@@ -1827,6 +1827,23 @@ snd_es1968_pcm(struct es1968 *chip, int device)
 
 	return 0;
 }
+/*
+ * suppress jitter on some maestros when playing stereo
+ */
+static void snd_es1968_suppress_jitter(struct es1968 *chip, struct esschan *es)
+{
+	unsigned int cp1;
+	unsigned int cp2;
+	unsigned int diff;
+
+	cp1 = __apu_get_register(chip, 0, 5);
+	cp2 = __apu_get_register(chip, 1, 5);
+	diff = (cp1 > cp2 ? cp1 - cp2 : cp2 - cp1);
+
+	if (diff > 1) {
+		__maestro_write(chip, IDR0_DATA_PORT, cp1);
+	}
+}
 
 /*
  * update pointer
@@ -1948,8 +1965,11 @@ static irqreturn_t snd_es1968_interrupt(int irq, void *dev_id)
 		struct esschan *es;
 		spin_lock(&chip->substream_lock);
 		list_for_each_entry(es, &chip->substream_list, list) {
-			if (es->running)
+			if (es->running) {
 				snd_es1968_update_pcm(chip, es);
+				if (es->fmt & ESS_FMT_STEREO)
+					snd_es1968_suppress_jitter(chip, es);
+			}
 		}
 		spin_unlock(&chip->substream_lock);
 		if (chip->in_measurement) {