[openwrt/openwrt] hostapd: introduce min_tx_power option

[LEDE Commits]

stintel pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/d2d5aabdbb947443b0d5f75c3847754c7c38a117

commit d2d5aabdbb947443b0d5f75c3847754c7c38a117
Author: Stijn Tintel <stijn at linux-ipv6.be>
AuthorDate: Mon Jun 27 17:06:34 2022 +0300

    hostapd: introduce min_tx_power option
    
    Introduce a new option min_tx_power to configure the minimum permitted
    max TX power (in dBm) for ACS and DFS channel selection.
    
    Imagine the following regulatory rules:
      * 5180 MHz [36] (21.0 dBm)
      * 5200 MHz [40] (21.0 dBm)
      * 5220 MHz [44] (21.0 dBm)
      * 5240 MHz [48] (21.0 dBm)
      * 5260 MHz [52] (20.0 dBm) (radar detection)
      * 5280 MHz [56] (20.0 dBm) (radar detection)
      * 5300 MHz [60] (20.0 dBm) (radar detection)
      * 5320 MHz [64] (20.0 dBm) (radar detection)
      * 5500 MHz [100] (21.0 dBm) (radar detection)
      * 5520 MHz [104] (21.0 dBm) (radar detection)
      * 5540 MHz [108] (21.0 dBm) (radar detection)
      * 5560 MHz [112] (21.0 dBm) (radar detection)
      * 5580 MHz [116] (21.0 dBm) (radar detection)
      * 5600 MHz [120] (21.0 dBm) (radar detection)
      * 5620 MHz [124] (21.0 dBm) (radar detection)
      * 5640 MHz [128] (21.0 dBm) (radar detection)
      * 5660 MHz [132] (21.0 dBm) (radar detection)
      * 5680 MHz [136] (21.0 dBm) (radar detection)
      * 5700 MHz [140] (21.0 dBm) (radar detection)
      * 5720 MHz [144] (13.0 dBm) (radar detection)
      * 5745 MHz [149] (13.0 dBm)
      * 5765 MHz [153] (13.0 dBm)
      * 5785 MHz [157] (13.0 dBm)
      * 5805 MHz [161] (13.0 dBm)
      * 5825 MHz [165] (13.0 dBm)
      * 5845 MHz [169] (13.0 dBm)
      * 5865 MHz [173] (13.0 dBm)
    
    When ACS or DFS end up selecting channel 144 or higher, some clients
    might no longer be able to communicate with the AP due to the TX power
    being limited to 13 dBm. Setting min_tx_power to 20 will result in
    hostapd not considering these channels during ACS or after a DFS event.
    
    Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
    Acked-by: David Bauer <mail at david-bauer.net>
---
 package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh b/package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh
index 3ffe6de66b..5d6ca7c0e3 100644
--- a/package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh
+++ b/package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh
@@ -28,7 +28,7 @@ drv_mac80211_init_device_config() {
 	config_add_string tx_burst
 	config_add_string distance
 	config_add_int beacon_int chanbw frag rts
-	config_add_int rxantenna txantenna antenna_gain txpower
+	config_add_int rxantenna txantenna antenna_gain txpower min_tx_power
 	config_add_boolean noscan ht_coex acs_exclude_dfs background_radar
 	config_add_array ht_capab
 	config_add_array channels
@@ -137,13 +137,15 @@ mac80211_hostapd_setup_base() {
 	[ -n "$acs_exclude_dfs" ] && [ "$acs_exclude_dfs" -gt 0 ] &&
 		append base_cfg "acs_exclude_dfs=1" "$N"
 
-	json_get_vars noscan ht_coex
+	json_get_vars noscan ht_coex min_tx_power:0
 	json_get_values ht_capab_list ht_capab tx_burst
 	json_get_values channel_list channels
 
 	[ "$auto_channel" = 0 ] && [ -z "$channel_list" ] && \
 		channel_list="$channel"
 
+	[ "$min_tx_power" -gt 0 ] && append base_cfg "min_tx_power=$min_tx_power"
+
 	set_default noscan 0
 
 	[ "$noscan" -gt 0 ] && hostapd_noscan=1