ath9k DFS failed -16 (Device or resource busy)

[Benoit]

Hi,

I am trying to run my AP on 5Ghz but I have some issue..
First of all I changed my country code thanks to CRDA to FR.

iw reg get
global
country FR: DFS-ETSI
     (2402 - 2482 @ 40), (N/A, 20), (N/A)
     (5170 - 5250 @ 80), (N/A, 20), (N/A), AUTO-BW
     (5250 - 5330 @ 80), (N/A, 20), (0 ms), DFS, AUTO-BW
     (5490 - 5710 @ 160), (N/A, 27), (0 ms), DFS
     (57000 - 66000 @ 2160), (N/A, 40), (N/A)

iw list
     Frequencies:
             * 5180 MHz [36] (15.0 dBm) (no IR)
             * 5200 MHz [40] (15.0 dBm) (no IR)
             * 5220 MHz [44] (15.0 dBm) (no IR)
             * 5240 MHz [48] (16.0 dBm) (no IR)
             * 5260 MHz [52] (15.0 dBm) (no IR, radar detection)
               DFS state: usable (for 924 sec)
               DFS CAC time: 60000 ms
             * 5280 MHz [56] (15.0 dBm) (no IR, radar detection)
               DFS state: usable (for 924 sec)
               DFS CAC time: 60000 ms
             * 5300 MHz [60] (15.0 dBm) (no IR, radar detection)
               DFS state: usable (for 924 sec)
               DFS CAC time: 60000 ms
             * 5320 MHz [64] (15.0 dBm) (no IR, radar detection)
               DFS state: usable (for 924 sec)
               DFS CAC time: 60000 ms
             * 5500 MHz [100] (17.0 dBm) (no IR, radar detection)
               DFS state: usable (for 924 sec)
               DFS CAC time: 60000 ms
             * 5520 MHz [104] (17.0 dBm) (no IR, radar detection)
               DFS state: usable (for 924 sec)

so I should be able to use channels 100-104 if I activate DFS, but I 
have an issue when I start hostap :
HT40: control channel: 104  secondary channel: 100
Completing interface initialization
Mode: IEEE 802.11a  Channel: 104  Frequency: 5520 MHz
DFS 2 channels required radar detection
DFS all channels available, (SKIP CAC): no
DFS 0 chans unavailable - choose other channel: no
pnic_wlan: interface state HT_SCAN->DFS
DFS start CAC on 5520 MHz
pnic_wlan: DFS-CAC-START freq=5520 chan=104 sec_chan=-1, width=0, 
seg0=0, seg1=0, cac_time=60s
nl80211: Start radar detection (CAC) 5520 MHz (ht_enabled=1, 
vht_enabled=0, bandwidth=40 MHz, cf1=5510 MHz, cf2=0 MHz)
   * freq=5520
   * vht_enabled=0
   * ht_enabled=1
   * sec_channel_offset=-1
   * channel_type=2
nl80211: Failed to start radar detection: -16 (Device or resource busy)
DFS start_dfs_cac() failed, -1
Interface initialization failed

I tried to compile my kernel module with the modified module but I only 
found one value (|ATH9K_DFS_CERTIFIED) but it doesn't change anything I 
keep having the same error message in hostap.

Just trying my luck here if anyone has some idea for me..
many thanks
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