dfs openwrt

# cat /etc/config/wireless

config wifi-device 'radio0'
	option type 'mac80211'
	option hwmode '11a'
	option path 'pci0000:00/0000:00:11.0'
	option txpower '1'
	option channel '120'  # 36 works great
	option country 'CZ'

config wifi-iface
	option device 'radio0'
	option mode 'ap'
	option ssid 'AP'
	option encryption 'psk2'
	option key '123456789'
	option network 'wifi'


# iw reg get
country CZ: DFS-ETSI
	(2400 - 2483 @ 40), (N/A, 20), (N/A)
	(5150 - 5250 @ 80), (N/A, 23), (N/A), NO-OUTDOOR
	(5250 - 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS
	(5470 - 5725 @ 160), (N/A, 27), (0 ms), DFS
	(57000 - 66000 @ 2160), (N/A, 40), (N/A)

I try channel 120 (5.60GHz). Iw reg allow 5.47-5.725GHz in my country. There is no problem.

I have compiled OpenWrt with DFS support:
5600 MHz [120] (27.0 dBm) (radar detection)
			  DFS state: usable (for 228 sec)
			  DFS CAC time: 60000 ms

# iw phy0 info
Wiphy phy0
	max # scan SSIDs: 4
	max scan IEs length: 2285 bytes
	Retry short limit: 7
	Retry long limit: 4
	Coverage class: 0 (up to 0m)
	Available Antennas: TX 0x3 RX 0x3
	Configured Antennas: TX 0x3 RX 0x3
	Supported interface modes:
		 * IBSS
		 * managed
		 * AP
		 * AP/VLAN
		 * monitor
		 * mesh point
	Band 1:
		Frequencies:
			* 2412 MHz [1] (20.0 dBm)
			* 2417 MHz [2] (20.0 dBm)
			* 2422 MHz [3] (20.0 dBm)
			* 2427 MHz [4] (20.0 dBm)
			* 2432 MHz [5] (20.0 dBm)
			* 2437 MHz [6] (20.0 dBm)
			* 2442 MHz [7] (20.0 dBm)
			* 2447 MHz [8] (20.0 dBm)
			* 2452 MHz [9] (20.0 dBm)
			* 2457 MHz [10] (20.0 dBm)
			* 2462 MHz [11] (20.0 dBm)
			* 2467 MHz [12] (20.0 dBm)
			* 2472 MHz [13] (20.0 dBm)
			* 2484 MHz [14] (disabled)
	Band 2:
		Frequencies:
			* 5040 MHz [8] (disabled)
			* 5060 MHz [12] (disabled)
			* 5080 MHz [16] (disabled)
			* 5180 MHz [36] (23.0 dBm)
			* 5200 MHz [40] (23.0 dBm)
			* 5220 MHz [44] (23.0 dBm)
			* 5240 MHz [48] (23.0 dBm)
			* 5260 MHz [52] (20.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5280 MHz [56] (20.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5300 MHz [60] (20.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5320 MHz [64] (20.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5500 MHz [100] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5520 MHz [104] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5540 MHz [108] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5560 MHz [112] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5580 MHz [116] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5600 MHz [120] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5620 MHz [124] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5640 MHz [128] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5660 MHz [132] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5680 MHz [136] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5700 MHz [140] (27.0 dBm) (radar detection)
			  DFS state: usable (for 54 sec)
			  DFS CAC time: 60000 ms
			* 5745 MHz [149] (disabled)
			* 5765 MHz [153] (disabled)
			* 5785 MHz [157] (disabled)
			* 5805 MHz [161] (disabled)
			* 5825 MHz [165] (disabled)
	valid interface combinations:
		 * #{ managed } <= 2048, #{ AP, mesh point } <= 4, #{ IBSS } <= 1,
		   total <= 2048, #channels <= 1
	HT Capability overrides:
		 * MCS: ff ff ff ff ff ff ff ff ff ff
		 * maximum A-MSDU length
		 * supported channel width
		 * short GI for 40 MHz
		 * max A-MPDU length exponent
		 * min MPDU start spacing
#