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cfg80211/mac80211: use reduced txpower for 5 and 10 MHz 

Some regulations (like germany, but also FCC) express their transmission
power limit in dBm/MHz or mW/MHz. To cope with that and be on the safe
side, reduce the maximum power to half (10 MHz) or quarter (5 MHz)
when operating on these reduced bandwidth channels.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
This commit is contained in:
Simon Wunderlich 2013-07-08 16:55:55 +02:00 committed by Johannes Berg
parent 74608aca4d
commit 0430c88347
4 changed files with 31 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
include/net/cfg80211.h
View File

@ -460,6 +460,33 @@ ieee80211_chandef_rate_flags(struct cfg80211_chan_def *chandef)
return 0;
}
/**
* ieee80211_chandef_max_power - maximum transmission power for the chandef
*
* In some regulations, the transmit power may depend on the configured channel
* bandwidth which may be defined as dBm/MHz. This function returns the actual
* max_power for non-standard (20 MHz) channels.
*
* @chandef: channel definition for the channel
*
* Returns: maximum allowed transmission power in dBm for the chandef
*/
static inline int
ieee80211_chandef_max_power(struct cfg80211_chan_def *chandef)
{
switch (chandef->width) {
case NL80211_CHAN_WIDTH_5:
return min(chandef->chan->max_reg_power - 6,
chandef->chan->max_power);
case NL80211_CHAN_WIDTH_10:
return min(chandef->chan->max_reg_power - 3,
chandef->chan->max_power);
default:
break;
}
return chandef->chan->max_power;
}
/**
* enum survey_info_flags - survey information flags
*

2
net/mac80211/iface.c
View File

@ -54,7 +54,7 @@ bool __ieee80211_recalc_txpower(struct ieee80211_sub_if_data *sdata)
return false;
}
power = chanctx_conf->def.chan->max_power;
power = ieee80211_chandef_max_power(&chanctx_conf->def);
rcu_read_unlock();
if (sdata->user_power_level != IEEE80211_UNSET_POWER_LEVEL)

2
net/mac80211/main.c
View File

@ -151,7 +151,7 @@ static u32 ieee80211_hw_conf_chan(struct ieee80211_local *local)
changed |= IEEE80211_CONF_CHANGE_SMPS;
}
power = chandef.chan->max_power;
power = ieee80211_chandef_max_power(&chandef);
rcu_read_lock();
list_for_each_entry_rcu(sdata, &local->interfaces, list) {

3
net/mac80211/mlme.c
View File

@ -747,7 +747,8 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
*pos++ = WLAN_EID_PWR_CAPABILITY;
*pos++ = 2;
*pos++ = 0; /* min tx power */
*pos++ = chan->max_power; /* max tx power */
/* max tx power */
*pos++ = ieee80211_chandef_max_power(&chanctx_conf->def);
/* 2. supported channels */
/* TODO: get this in reg domain format */