mac80211: Accept auto txpower setting

This changes the SIWTXPOWER ioctl to also accept a txpower setting of
"automatic". Since mac80211 currently cannot tell drivers to automatically
adjust tx power, we select the tx power level of the current channel. While
this is kind of a hack, it certainly saves some iwconfig users from headaches.

Signed-off-by: Mattias Nissler <mattias.nissler@gmx.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 4 deletions

diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index 308bbe4a1333..da3350d44da1 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -634,22 +634,35 @@ static int ieee80211_ioctl_siwtxpower(struct net_device *dev,
 {
         struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
         bool need_reconfig = 0;
+        u8 new_power_level;
 
         if ((data->txpower.flags & IW_TXPOW_TYPE) != IW_TXPOW_DBM)
                 return -EINVAL;
         if (data->txpower.flags & IW_TXPOW_RANGE)
                 return -EINVAL;
-        if (!data->txpower.fixed)
-                return -EINVAL;
 
-        if (local->hw.conf.power_level != data->txpower.value) {
-                local->hw.conf.power_level = data->txpower.value;
+        if (data->txpower.fixed) {
+                new_power_level = data->txpower.value;
+        } else {
+                /* Automatic power level. Get the px power from the current
+                 * channel. */
+                struct ieee80211_channel* chan = local->oper_channel;
+                if (!chan)
+                        return -EINVAL;
+
+                new_power_level = chan->power_level;
+        }
+
+        if (local->hw.conf.power_level != new_power_level) {
+                local->hw.conf.power_level = new_power_level;
                 need_reconfig = 1;
         }
+
         if (local->hw.conf.radio_enabled != !(data->txpower.disabled)) {
                 local->hw.conf.radio_enabled = !(data->txpower.disabled);
                 need_reconfig = 1;
         }
+
         if (need_reconfig) {
                 ieee80211_hw_config(local);
                 /* The return value of hw_config is not of big interest here,