ath9k: Fix RX interrupt mitigation

The threshold values for RX interrupt mitigation
are different for AR9003 and AR9002 families.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index ce41658..fbf43c0 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -358,6 +358,14 @@
 
 	ah->config.rx_intr_mitigation = true;
 
+	if (AR_SREV_9300_20_OR_LATER(ah)) {
+		ah->config.rimt_last = 500;
+		ah->config.rimt_first = 2000;
+	} else {
+		ah->config.rimt_last = 250;
+		ah->config.rimt_first = 700;
+	}
+
 	/*
 	 * We need this for PCI devices only (Cardbus, PCI, miniPCI)
 	 * _and_ if on non-uniprocessor systems (Multiprocessor/HT).
@@ -1876,8 +1884,8 @@
 		REG_WRITE(ah, AR_OBS, 8);
 
 	if (ah->config.rx_intr_mitigation) {
-		REG_RMW_FIELD(ah, AR_RIMT, AR_RIMT_LAST, 500);
-		REG_RMW_FIELD(ah, AR_RIMT, AR_RIMT_FIRST, 2000);
+		REG_RMW_FIELD(ah, AR_RIMT, AR_RIMT_LAST, ah->config.rimt_last);
+		REG_RMW_FIELD(ah, AR_RIMT, AR_RIMT_FIRST, ah->config.rimt_first);
 	}
 
 	if (ah->config.tx_intr_mitigation) {