Aparement le probleme vient du noyau, mes recherches sur Google relatent le meme phénomène sur differentes distributions, j'ai lu des topics sur Ubuntu, Archlinux entre autres...
Chez moi un dmesg | grep ath9k retourne :
ath9k 0000:02:00.0: PCI INT A --> GSI 17 (level , low) --> IRQ17
ath9k 0000:02:00.0: setting latency timer to 64
ieee80211 phy0: Selected rate control algorithm 'ath9k_rate_control'
le reste concerne la led indiquant l'usage du wifi.
Après reactivation du wifi par FN=F3 :
root@localhost ~]# dmesg | grep wlan0
[ 26.344660] ADDRCONF(NETDEV_UP): wlan0: link is not ready
[ 30.223511] wlan0: authenticate with 00:24:d4:c9:70:74 (try 1)
[ 30.239128] wlan0: authenticated
[ 30.284579] wlan0: associate with 00:24:d4:c9:70:74 (try 1)
[ 30.312484] wlan0: RX AssocResp from 00:24:d4:c9:70:74 (capab=0x411 status=0 aid=1)
[ 30.312493] wlan0: associated
[ 30.321041] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[ 42.018050] wlan0: no IPv6 routers present
[ 717.762514] wlan0: deauthenticating from 00:24:d4:c9:70:74 by local choice (reason=3)
[ 745.681413] ADDRCONF(NETDEV_UP): wlan0: link is not ready
[ 748.670684] wlan0: authenticate with 00:24:d4:c9:70:74 (try 1)
[ 748.676972] wlan0: authenticated
[ 748.718472] wlan0: associate with 00:24:d4:c9:70:74 (try 1)
[ 748.722052] wlan0: RX AssocResp from 00:24:d4:c9:70:74 (capab=0x411 status=0 aid=1)
[ 748.722063] wlan0: associated
[ 748.733617] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[ 759.522059] wlan0: no IPv6 routers present
]# iwconfig
lo no wireless extensions.
em1 no wireless extensions.
wlan0 IEEE 802.11bgn ESSID:"freeboxedom"
Mode:Managed Frequency:2.462 GHz Access Point: 00:24:D4:C9:70:74
Bit Rate=65 Mb/s Tx-Power=14 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:on
Link Quality=70/70 Signal level=-26 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:17 Invalid misc:22 Missed beacon: