wireless: Save original maximum regulatory transmission power for the calucation of the local maximum transmit power

The local maximum transmit power is the maximum power a wireless device
allowed to transmit. If Power Constraint is presented, the local maximum
power equals to the maximum allowed power defined in regulatory domain
minus power constraint.

The maximum transmit power is maximum power a wireless device capable of
transmitting, and should be used in Power Capability element (7.3.2.16
IEEE802.11 2007).

The transmit power from a wireless device should not greater than the
local maximum transmit power.

The maximum transmit power was not calculated correctly in the current
Linux wireless/mac80211 when Power Constraint is presented.

Signed-off-by: Hong Wu <hong.wu@dspg.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/cfg80211.h

@@ -120,6 +120,7 @@ enum ieee80211_channel_flags {
  * @band: band this channel belongs to.
  * @max_antenna_gain: maximum antenna gain in dBi
  * @max_power: maximum transmission power (in dBm)
+ * @max_reg_power: maximum regulatory transmission power (in dBm)
  * @beacon_found: helper to regulatory code to indicate when a beacon
  *	has been found on this channel. Use regulatory_hint_found_beacon()
  *	to enable this, this is useful only on 5 GHz band.
@@ -133,6 +134,7 @@ struct ieee80211_channel {
 	u32 flags;
 	int max_antenna_gain;
 	int max_power;
+	int max_reg_power;
 	bool beacon_found;
 	u32 orig_flags;
 	int orig_mag, orig_mpwr;

net/wireless/reg.c

@@ -882,23 +882,8 @@ static void handle_channel(struct wiphy *wiphy,
 	chan->flags = flags | bw_flags | map_regdom_flags(reg_rule->flags);
 	chan->max_antenna_gain = min(chan->orig_mag,
 		(int) MBI_TO_DBI(power_rule->max_antenna_gain));
-	if (chan->orig_mpwr) {
-		/*
-		 * Devices that have their own custom regulatory domain
-		 * but also use WIPHY_FLAG_STRICT_REGULATORY will follow the
-		 * passed country IE power settings.
-		 */
-		if (initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE &&
-		    wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY &&
-		    wiphy->flags & WIPHY_FLAG_STRICT_REGULATORY) {
-			chan->max_power =
-				MBM_TO_DBM(power_rule->max_eirp);
-		} else {
-			chan->max_power = min(chan->orig_mpwr,
-				(int) MBM_TO_DBM(power_rule->max_eirp));
-		}
-	} else
-		chan->max_power = (int) MBM_TO_DBM(power_rule->max_eirp);
+	chan->max_reg_power = (int) MBM_TO_DBM(power_rule->max_eirp);
+	chan->max_power = min(chan->max_power, chan->max_reg_power);
 }
 
 static void handle_band(struct wiphy *wiphy,