mac80211: Fix the maximum transmit power with power constraint

The local maximum transmit power for a channel is defined as the maximum
regulatory transmission power minus the local power constraint specified
for the channel in the Power Constraint element. (7.3.2.15 IEEE80211 2007)

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

net/mac80211/main.c

@@ -155,7 +155,8 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 		power = chan->max_power;
 	else
 		power = local->power_constr_level ?
-			(chan->max_power - local->power_constr_level) :
+			min(chan->max_power,
+				(chan->max_reg_power  - local->power_constr_level)) :
 			chan->max_power;
 
 	if (local->user_power_level >= 0)

net/mac80211/mlme.c

@@ -547,7 +547,7 @@ static void ieee80211_handle_pwr_constr(struct ieee80211_sub_if_data *sdata,
 	if (pwr_constr_elem_len != 1)
 		return;
 
-	if ((*pwr_constr_elem <= conf->channel->max_power) &&
+	if ((*pwr_constr_elem <= conf->channel->max_reg_power) &&
 	    (*pwr_constr_elem != sdata->local->power_constr_level)) {
 		sdata->local->power_constr_level = *pwr_constr_elem;
 		ieee80211_hw_config(sdata->local, 0);