ath9k: Reduce the frequency of PA offset calibration

PA calibration need not be done if the offset is not varying.
The current logic does PA calibration even if the offset is the
same.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -861,7 +861,7 @@ static void ath9k_hw_9271_pa_cal(struct ath_hw *ah)
 		REG_WRITE(ah, regList[i][0], regList[i][1]);
 }
 
-static inline void ath9k_hw_9285_pa_cal(struct ath_hw *ah)
+static inline void ath9k_hw_9285_pa_cal(struct ath_hw *ah, bool is_reset)
 {
 
 	u32 regVal;
@@ -877,6 +877,8 @@ static inline void ath9k_hw_9285_pa_cal(struct ath_hw *ah)
 		{ 0x7838, 0 },
 	};
 
+	DPRINTF(ah->ah_sc, ATH_DBG_CALIBRATE, "Running PA Calibration\n");
+
 	if (AR_SREV_9285_11(ah)) {
 		REG_WRITE(ah, AR9285_AN_TOP4, (AR9285_AN_TOP4_DEFAULT | 0x14));
 		udelay(10);
@@ -936,6 +938,17 @@ static inline void ath9k_hw_9285_pa_cal(struct ath_hw *ah)
 	offs_6_1 = offset>>1;
 	offs_0 = offset & 1;
 
+	if ((!is_reset) && (ah->pacal_info.prev_offset == offset)) {
+		if (ah->pacal_info.max_skipcount < MAX_PACAL_SKIPCOUNT)
+			ah->pacal_info.max_skipcount =
+				2 * ah->pacal_info.max_skipcount;
+		ah->pacal_info.skipcount = ah->pacal_info.max_skipcount;
+	} else {
+		ah->pacal_info.max_skipcount = 1;
+		ah->pacal_info.skipcount = 0;
+		ah->pacal_info.prev_offset = offset;
+	}
+
 	REG_RMW_FIELD(ah, AR9285_AN_RF2G6, AR9285_AN_RF2G6_OFFS, offs_6_1);
 	REG_RMW_FIELD(ah, AR9285_AN_RF2G3, AR9285_AN_RF2G3_PDVCCOMP, offs_0);
 
@@ -982,8 +995,12 @@ bool ath9k_hw_calibrate(struct ath_hw *ah, struct ath9k_channel *chan,
 		/* Do periodic PAOffset Cal */
 		if (AR_SREV_9271(ah))
 			ath9k_hw_9271_pa_cal(ah);
-		else if (AR_SREV_9285_11_OR_LATER(ah))
-			ath9k_hw_9285_pa_cal(ah);
+		else if (AR_SREV_9285_11_OR_LATER(ah)) {
+			if (!ah->pacal_info.skipcount)
+				ath9k_hw_9285_pa_cal(ah, false);
+			else
+				ah->pacal_info.skipcount--;
+		}
 
 		if (OLC_FOR_AR9280_20_LATER || OLC_FOR_AR9287_10_LATER)
 			ath9k_olc_temp_compensation(ah);
@@ -1081,7 +1098,7 @@ bool ath9k_hw_init_cal(struct ath_hw *ah, struct ath9k_channel *chan)
 
 	/* Do PA Calibration */
 	if (AR_SREV_9285_11_OR_LATER(ah))
-		ath9k_hw_9285_pa_cal(ah);
+		ath9k_hw_9285_pa_cal(ah, true);
 
 	/* Do NF Calibration after DC offset and other calibrations */
 	REG_WRITE(ah, AR_PHY_AGC_CONTROL,