wifi-scripts: txpower 0 treated as auto in ucode mac80211.sh — router transmits at maximum power

Describe the bug

When setting option txpower '0' in /etc/config/wireless, the router ignores the value and transmits at maximum power. The bug is in the ucode version of mac80211.sh — txpower 0 is falsy in ucode/JavaScript, causing the script to set txpower to auto instead of fixed 000. The old shell version correctly handles 0 using [ -n "$txpower" ]. The bug was introduced during migration to ucode.

OpenWrt version

r32802-f505120278

OpenWrt release

25.12.2

OpenWrt target/subtarget

Multiple targets affected: mediatek/filogic, ath79/generic, ath79/generic (ipq40xx)

Device

Multiple devices affected — see additional info

Image kind

Official downloaded image

Steps to reproduce

uci set wireless.radio1.txpower='0'
uci commit wireless
wifi reload
iwinfo phy1-ap0 info | grep Tx-Power

Actual behaviour

Tx-Power: 23 dBm — maximum power despite txpower=0

Expected behaviour

Tx-Power: 0 dBm — or minimum supported by hardware

Additional info

Root cause:
In package/network/config/wifi-scripts/files-ucode/lib/netifd/wireless/mac80211.sh:

Bug — 0 is falsy in ucode, jumps to auto:
if (config.txpower)
config.txpower = 'fixed ' + config.txpower + '00';
else
config.txpower = 'auto';

Fix — explicit null check:
if (config.txpower != null)
config.txpower = 'fixed ' + config.txpower + '00';
else
config.txpower = 'auto';

Note: The old shell version uses [ -n "$txpower" ] which correctly handles 0.
The bug was introduced during migration to ucode.

Confirmed active version is ucode:
cat /lib/netifd/wireless/mac80211.sh | head -5
#!/usr/bin/ucode
'use strict';
import { set_default, log } from 'wifi.common';

Proof — direct iw command works correctly:
iw phy phy1 set txpower fixed 0
iwinfo phy1-ap0 info | grep Tx-Power
Tx-Power: 0 dBm

The kernel driver accepts 0 dBm correctly — the bug is in the ucode script, not the kernel driver.

Proof — after wifi reload, txpower is absent from configuration line:
netifd: radio1 (12995): wifi-scripts: Configuring 'phy1' txantenna: 4294967295, rxantenna: 4294967295 distance: 0

txpower is absent — confirming it was set to auto instead of fixed 000.

Also note:
netifd: radio1 (4936): command failed: Not supported (-95)
This error appears because the ucode script attempts to set txpower auto on a phy that does not support it.

Tested on five devices with three different chipsets, all running OpenWrt 25.12.2:

Device | Chipset | txpower=1 | txpower=0
Cudy WR3000S v1 | MediaTek Filogic | 1 dBm | 23 dBm
Buffalo WZR-600DHP | Atheros AR7161 | 3 dBm | 15 dBm
OpenWrt One | MediaTek Filogic | 1 dBm | 23 dBm
TP-Link Archer C7 v2 | Qualcomm Atheros QCA9558 | 5 dBm | 25 dBm
GL.iNet GL-MT6000 | MediaTek Filogic | 1 dBm | 23 dBm

All devices show identical behavior — this is not chipset specific.

Physical verification:
At txpower=0: -51 dBm measured by nearby router
At txpower=1: -72 dBm measured by nearby router

The 21 dBm difference confirms the router is transmitting at maximum power when txpower=0 is set.

UCI stores the value correctly:
uci show wireless.radio1
wireless.radio1.txpower='0'

UCI correctly stores and returns the value — the bug is exclusively in the ucode script.

Related issue in openwrt/luci: https://github.com/openwrt/luci/issues/8177

Diffconfig

Not applicable — official image

Terms

• I am reporting an issue for OpenWrt, not an unsupported fork.

Start in package/network/config/wifi-scripts/files-ucode/lib/netifd/wireless/mac80211.sh and inspect the txpower handling described in the issue. Reproduce with the provided UCI, wifi reload, and iwinfo commands on an affected device. Done means txpower='0' is passed as fixed 000 rather than auto and the reported power is 0 dBm or the hardware minimum.