ath9k ap/client did not acknowledge authentication response

[Daniel Halperin]

Hi everyone, I'm having association problems between very close
devices on a very strong link (150 Mbps TCP when it associates).

I have AR9380 ath9k devices for AP and client, running latest
wireless-testing.git kernel and hostap-07.git. The salient parts of
hostapd.conf look like this:

channel=60
hw_mode=a
ht_capab=[HT40+]

It often takes the client 3 or 4 tries to associate to the AP. The
client thinks it is associated, but the AP does not. Here's a failed
attempt:

wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: authentication OK (open system)
wlan1: STA 00:0e:8e:30:f9:3b MLME:
MLME-AUTHENTICATE.indication(00:0e:8e:30:f9:3b, OPEN_SYSTEM)
wlan1: STA 00:0e:8e:30:f9:3b MLME: MLME-DELETEKEYS.request(00:0e:8e:30:f9:3b)
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: association OK (aid 1)
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: did not acknowledge
authentication response
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: did not acknowledge
association response
wlan1: AP-STA-DISCONNECTED 00:0e:8e:30:f9:3b
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: deauthenticated
wlan1: STA 00:0e:8e:30:f9:3b MLME:
MLME-DEAUTHENTICATE.indication(00:0e:8e:30:f9:3b, 3)
wlan1: STA 00:0e:8e:30:f9:3b MLME: MLME-DELETEKEYS.request(00:0e:8e:30:f9:3b)

here's a successful attempt:

wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: authentication OK (open system)
wlan1: STA 00:0e:8e:30:f9:3b MLME:
MLME-AUTHENTICATE.indication(00:0e:8e:30:f9:3b, OPEN_SYSTEM)
wlan1: STA 00:0e:8e:30:f9:3b MLME: MLME-DELETEKEYS.request(00:0e:8e:30:f9:3b)
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: authenticated
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: association OK (aid 1)
wlan1: STA 00:0e:8e:30:f9:3b IEEE 802.11: associated (aid 1)
wlan1: AP-STA-CONNECTED 00:0e:8e:30:f9:3b
wlan1: STA 00:0e:8e:30:f9:3b MLME: MLME-ASSOCIATE.indication(00:0e:8e:30:f9:3b)
wlan1: STA 00:0e:8e:30:f9:3b MLME: MLME-DELETEKEYS.request(00:0e:8e:30:f9:3b)

Any ideas what to do next?

Thanks,
Dan