mac80211: ignore AP power level when tx power type is "fixed"

In some cases a user might want to connect to a far away access point,
which announces a low tx power limit. Using the AP's power limit can
make the connection significantly more unstable or even impossible, and
mac80211 currently provides no way to disable this behavior.

To fix this, use the currently unused distinction between limited and
fixed tx power to decide whether a remote AP's power limit should be
accepted.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Alexandre Frade <kernel@xanmod.org>

net/mac80211/iface.c

@@ -63,7 +63,8 @@ bool __ieee80211_recalc_txpower(struct ieee80211_sub_if_data *sdata)
 	if (sdata->deflink.user_power_level != IEEE80211_UNSET_POWER_LEVEL)
 		power = min(power, sdata->deflink.user_power_level);
 
-	if (sdata->deflink.ap_power_level != IEEE80211_UNSET_POWER_LEVEL)
+	if (sdata->deflink.ap_power_level != IEEE80211_UNSET_POWER_LEVEL &&
+	    sdata->vif.bss_conf.txpower_type != NL80211_TX_POWER_FIXED)
 		power = min(power, sdata->deflink.ap_power_level);
 
 	if (power != sdata->vif.bss_conf.txpower) {