ath9k_hw: use standard SIFS time as reference for half/quarter channels

Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/hw.c

@@ -1041,6 +1041,11 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 		rx_lat = 37;
 	tx_lat = 54;
 
+	if (IS_CHAN_5GHZ(chan))
+		sifstime = 16;
+	else
+		sifstime = 10;
+
 	if (IS_CHAN_HALF_RATE(chan)) {
 		eifs = 175;
 		rx_lat *= 2;
@@ -1048,8 +1053,8 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 		if (IS_CHAN_A_FAST_CLOCK(ah, chan))
 		    tx_lat += 11;
 
+		sifstime *= 2;
 		slottime = 13;
-		sifstime = 32;
 	} else if (IS_CHAN_QUARTER_RATE(chan)) {
 		eifs = 340;
 		rx_lat = (rx_lat * 4) - 1;
@@ -1057,8 +1062,8 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 		if (IS_CHAN_A_FAST_CLOCK(ah, chan))
 		    tx_lat += 22;
 
+		sifstime *= 4;
 		slottime = 21;
-		sifstime = 64;
 	} else {
 		if (AR_SREV_9287(ah) && AR_SREV_9287_13_OR_LATER(ah)) {
 			eifs = AR_D_GBL_IFS_EIFS_ASYNC_FIFO;
@@ -1072,10 +1077,6 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 		tx_lat = MS(reg, AR_USEC_TX_LAT);
 
 		slottime = ah->slottime;
-		if (IS_CHAN_5GHZ(chan))
-			sifstime = 16;
-		else
-			sifstime = 10;
 	}
 
 	/* As defined by IEEE 802.11-2007 17.3.8.6 */