rt2x00: Don't recalculate HT40 compensation for each rate

Previously the HT40 tx power compensation value was calculated for each
rate. However, the calculation is independent of the tx rate and as such
can be precalculated and just passed in for each rate.
Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800lib.c

@@ -1861,7 +1861,8 @@ static u8 rt2800_compesate_txpower(struct rt2x00_dev *rt2x00dev,
 				     int is_rate_b,
 				     enum ieee80211_band band,
 				     int power_level,
-				     u8 txpower)
+				     u8 txpower,
+				     int delta)
 {
 	u32 reg;
 	u16 eeprom;
@@ -1869,13 +1870,10 @@ static u8 rt2800_compesate_txpower(struct rt2x00_dev *rt2x00dev,
 	u8 eirp_txpower;
 	u8 eirp_txpower_criterion;
 	u8 reg_limit;
-	int bw_comp;
 
 	if (!((band == IEEE80211_BAND_5GHZ) && is_rate_b))
 		return txpower;
 
-	bw_comp = rt2800_get_txpower_bw_comp(rt2x00dev, band);
-
 	if (test_bit(CONFIG_SUPPORT_POWER_LIMIT, &rt2x00dev->flags)) {
 		/*
 		 * Check if eirp txpower exceed txpower_limit.
@@ -1898,14 +1896,14 @@ static u8 rt2800_compesate_txpower(struct rt2x00_dev *rt2x00dev,
 						 EEPROM_EIRP_MAX_TX_POWER_5GHZ);
 
 		eirp_txpower = eirp_txpower_criterion + (txpower - criterion) +
-				       (is_rate_b ? 4 : 0) + bw_comp;
+			       (is_rate_b ? 4 : 0) + delta;
 
 		reg_limit = (eirp_txpower > power_level) ?
 					(eirp_txpower - power_level) : 0;
 	} else
 		reg_limit = 0;
 
-	return txpower + bw_comp - reg_limit;
+	return txpower + delta - reg_limit;
 }
 
 static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
@@ -1919,6 +1917,12 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 	u32 offset;
 	enum ieee80211_band band = conf->channel->band;
 	int power_level = conf->power_level;
+	int delta;
+
+	/*
+	 * Calculate HT40 compensation delta
+	 */
+	delta = rt2800_get_txpower_bw_comp(rt2x00dev, band);
 
 	/*
 	 * set to normal bbp tx power control mode: +/- 0dBm
@@ -1948,7 +1952,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE0);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE0, txpower);
 
 		/*
@@ -1959,7 +1963,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE1);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE1, txpower);
 
 		/*
@@ -1970,7 +1974,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE2);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE2, txpower);
 
 		/*
@@ -1981,7 +1985,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE3);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE3, txpower);
 
 		/* read the next four txpower values */
@@ -1997,7 +2001,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE0);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE4, txpower);
 
 		/*
@@ -2008,7 +2012,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE1);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE5, txpower);
 
 		/*
@@ -2019,7 +2023,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE2);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE6, txpower);
 
 		/*
@@ -2030,7 +2034,7 @@ static void rt2800_config_txpower(struct rt2x00_dev *rt2x00dev,
 		txpower = rt2x00_get_field16(eeprom,
 					     EEPROM_TXPOWER_BYRATE_RATE3);
 		txpower = rt2800_compesate_txpower(rt2x00dev, is_rate_b, band,
-					     power_level, txpower);
+					     power_level, txpower, delta);
 		rt2x00_set_field32(&reg, TX_PWR_CFG_RATE7, txpower);
 
 		rt2800_register_write(rt2x00dev, offset, reg);