diff --git a/drivers/net/wireless/ath/ar9170/hw.h b/drivers/net/wireless/ath/ar9170/hw.h
index 95bf812d6fcc8d7bbb1de58e222d8fe9f9ca2760..3293e0fb24fbc79a4a62cb3e7c75ace3f7b9ba76 100644
--- a/drivers/net/wireless/ath/ar9170/hw.h
+++ b/drivers/net/wireless/ath/ar9170/hw.h
@@ -207,6 +207,8 @@ enum ar9170_cmd {
 #define AR9170_MAC_REG_AC1_AC0_TXOP		(AR9170_MAC_REG_BASE + 0xB44)
 #define AR9170_MAC_REG_AC3_AC2_TXOP		(AR9170_MAC_REG_BASE + 0xB48)
 
+#define AR9170_MAC_REG_AMPDU_SET		(AR9170_MAC_REG_BASE + 0xba0)
+
 #define AR9170_MAC_REG_ACK_TABLE		(AR9170_MAC_REG_BASE + 0xC00)
 #define AR9170_MAC_REG_AMPDU_RX_THRESH		(AR9170_MAC_REG_BASE + 0xC50)
 
diff --git a/drivers/net/wireless/ath/ar9170/mac.c b/drivers/net/wireless/ath/ar9170/mac.c
index 0e5967dd119c2e589c50e8bdbb28e94409b00222..45986b6eadbc06c736d0986a28dae7276bc575bd 100644
--- a/drivers/net/wireless/ath/ar9170/mac.c
+++ b/drivers/net/wireless/ath/ar9170/mac.c
@@ -72,6 +72,24 @@ int ar9170_set_qos(struct ar9170 *ar)
 	return ar9170_regwrite_result();
 }
 
+static int ar9170_set_ampdu_density(struct ar9170 *ar, u8 mpdudensity)
+{
+	u32 val;
+
+	/* don't allow AMPDU density > 8us */
+	if (mpdudensity > 6)
+		return -EINVAL;
+
+	/* Watch out! Otus uses slightly different density values. */
+	val = 0x140a00 | (mpdudensity ? (mpdudensity + 1) : 0);
+
+	ar9170_regwrite_begin(ar);
+	ar9170_regwrite(AR9170_MAC_REG_AMPDU_SET, val);
+	ar9170_regwrite_finish();
+
+	return ar9170_regwrite_result();
+}
+
 int ar9170_init_mac(struct ar9170 *ar)
 {
 	ar9170_regwrite_begin(ar);
@@ -296,6 +314,11 @@ int ar9170_set_operating_mode(struct ar9170 *ar)
 	if (err)
 		return err;
 
+	/* set AMPDU density to 8us. */
+	err = ar9170_set_ampdu_density(ar, 6);
+	if (err)
+		return err;
+
 	ar9170_regwrite_begin(ar);
 
 	ar9170_regwrite(AR9170_MAC_REG_POWERMANAGEMENT, pm_mode);
diff --git a/drivers/net/wireless/ath/ar9170/main.c b/drivers/net/wireless/ath/ar9170/main.c
index 3bd3a61225cea3be9c3a7ea97e8265ade38ef498..4ef1d2fc859c47c8dac22686a3ac72b67a99987f 100644
--- a/drivers/net/wireless/ath/ar9170/main.c
+++ b/drivers/net/wireless/ath/ar9170/main.c
@@ -151,8 +151,8 @@ static struct ieee80211_channel ar9170_5ghz_chantable[] = {
 			  IEEE80211_HT_CAP_SGI_40 |			\
 			  IEEE80211_HT_CAP_DSSSCCK40 |			\
 			  IEEE80211_HT_CAP_SM_PS,			\
-	.ampdu_factor	= 3, /* ?? */					\
-	.ampdu_density	= 7, /* ?? */					\
+	.ampdu_factor	= 3,						\
+	.ampdu_density	= 6,						\
 	.mcs		= {						\
 		.rx_mask = { 0xFF, 0xFF, 0, 0, 0, 0, 0, 0, 0, 0, },	\
 	},								\