ath9k_hw: Fix throughput drops in HT40 mode for AR9287 chips

Doing adc gain calibration for AR9287 chips is causing
throughput drops in HT40 mode. Remove ADC Gain from supported
calibration list.
Signed-off-by: NRajkumar Manoharan <rmanoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ar9002_calib.c

@@ -26,6 +26,27 @@ enum ar9002_cal_types {
 	IQ_MISMATCH_CAL = BIT(2),
 };
 
+static bool ar9002_hw_is_cal_supported(struct ath_hw *ah,
+				struct ath9k_channel *chan,
+				enum ar9002_cal_types cal_type)
+{
+	bool supported = false;
+	switch (ah->supp_cals & cal_type) {
+	case IQ_MISMATCH_CAL:
+		/* Run IQ Mismatch for non-CCK only */
+		if (!IS_CHAN_B(chan))
+			supported = true;
+		break;
+	case ADC_GAIN_CAL:
+	case ADC_DC_CAL:
+		/* Run ADC Gain Cal for non-CCK & non 2GHz-HT20 only */
+		if (!IS_CHAN_B(chan) &&
+		    !(IS_CHAN_2GHZ(chan) && IS_CHAN_HT20(chan)))
+			supported = true;
+		break;
+	}
+	return supported;
+}
 
 static void ar9002_hw_setup_calibration(struct ath_hw *ah,
 					struct ath9k_cal_list *currCal)
@@ -858,26 +879,32 @@ static bool ar9002_hw_init_cal(struct ath_hw *ah, struct ath9k_channel *chan)
 	if (AR_SREV_9100(ah) || AR_SREV_9160_10_OR_LATER(ah)) {
 		ah->supp_cals = IQ_MISMATCH_CAL;
 
-		if (AR_SREV_9160_10_OR_LATER(ah) &&
-		    !(IS_CHAN_2GHZ(chan) && IS_CHAN_HT20(chan))) {
+		if (AR_SREV_9160_10_OR_LATER(ah))
 			ah->supp_cals |= ADC_GAIN_CAL | ADC_DC_CAL;
 
+		if (AR_SREV_9287(ah))
+			ah->supp_cals &= ~ADC_GAIN_CAL;
 
+		if (ar9002_hw_is_cal_supported(ah, chan, ADC_GAIN_CAL)) {
 			INIT_CAL(&ah->adcgain_caldata);
 			INSERT_CAL(ah, &ah->adcgain_caldata);
 			ath_dbg(common, ATH_DBG_CALIBRATE,
-				"enabling ADC Gain Calibration.\n");
+					"enabling ADC Gain Calibration.\n");
+		}
 
+		if (ar9002_hw_is_cal_supported(ah, chan, ADC_DC_CAL)) {
 			INIT_CAL(&ah->adcdc_caldata);
 			INSERT_CAL(ah, &ah->adcdc_caldata);
 			ath_dbg(common, ATH_DBG_CALIBRATE,
-				"enabling ADC DC Calibration.\n");
+					"enabling ADC DC Calibration.\n");
 		}
 
-		INIT_CAL(&ah->iq_caldata);
-		INSERT_CAL(ah, &ah->iq_caldata);
-		ath_dbg(common, ATH_DBG_CALIBRATE,
-			"enabling IQ Calibration.\n");
+		if (ar9002_hw_is_cal_supported(ah, chan, IQ_MISMATCH_CAL)) {
+			INIT_CAL(&ah->iq_caldata);
+			INSERT_CAL(ah, &ah->iq_caldata);
+			ath_dbg(common, ATH_DBG_CALIBRATE,
+					"enabling IQ Calibration.\n");
+		}
 
 		ah->cal_list_curr = ah->cal_list;