ath9k_hw: disable Tx IQ calibration on half/quarter channels

It does not work properly and reduces throughput.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ar9003_calib.c

@@ -1000,10 +1000,12 @@ static bool ar9003_hw_init_cal(struct ath_hw *ah,
 	if (mci && IS_CHAN_2GHZ(chan) && run_agc_cal)
 		ar9003_mci_init_cal_req(ah, &is_reusable);
 
-	txiqcal_done = ar9003_hw_tx_iq_cal_run(ah);
-	REG_WRITE(ah, AR_PHY_ACTIVE, AR_PHY_ACTIVE_DIS);
-	udelay(5);
-	REG_WRITE(ah, AR_PHY_ACTIVE, AR_PHY_ACTIVE_EN);
+	if (!(IS_CHAN_HALF_RATE(chan) || IS_CHAN_QUARTER_RATE(chan))) {
+		txiqcal_done = ar9003_hw_tx_iq_cal_run(ah);
+		REG_WRITE(ah, AR_PHY_ACTIVE, AR_PHY_ACTIVE_DIS);
+		udelay(5);
+		REG_WRITE(ah, AR_PHY_ACTIVE, AR_PHY_ACTIVE_EN);
+	}
 
 skip_tx_iqcal:
 	if (run_agc_cal || !(ah->ah_flags & AH_FASTCC)) {