Linux kernel wireless device driver

Question

I can't understand one thing in net/wireless/nl80211.c file starting from kernel 3.13. Why there is following if statement in nl80211_start_radar_detection():

if (netif_carrier_ok(dev)) {
    return -EBUSY;
}

From what I understand this means that we cannot start radar detection if our driver carrier is ready. Why? Shouldn't that be

if (!netif_carrier_ok(dev)) {
    return -EBUSY;
}

Thanks

Answer 1

nl80211_start_radar_detection（）： - 这将启动雷达探测，如果检测到雷达，将从​​通道移动。

但是这里是netif_carrier_ok（dev），检查设备是否支持该载波，或者我的设备是否可以在该通道上运行，如果没有返回错误。

无需继续操作并检查雷达。