ath5k: problems during the connection to a sitecom AP

[Fabio Rossi <rossi.f@inwind.it>]

I'm testing the ath5k driver (wireless-testing v2.6.28-rc4-5172-gc1a847c) with 
my 3com 3CRDAG675 PCI card (atheros AR5212). I can try alternatively two 
different access points (both configured with WEP + hidden SSID), the 
procedure I use is the same but the results are different.

Here are the commands used:

modprobe ath5k
ifconfig ath0 192.168.1.2 up
iwconfig ath0 key <MYKEY>
iwconfig ath0 ap <AP_MAC>
iwconfig ath0 essid <MY_ESSID>


*** 3com AP ***
With this one I can associate without problems at the first try (SSID not 
broadcast + WEP encryption):

ath5k_pci 0000:00:0b.0: PCI INT A -> Link[LNKB] -> GSI 10 (level, low) -> IRQ 
10
ath5k_pci 0000:00:0b.0: registered as 'phy1'
phy1: Selected rate control algorithm 'minstrel'
ath5k phy1: Atheros AR5212 chip found (MAC: 0x56, PHY: 0x41)
ath5k phy1: RF5112B multiband radio found (0x36)
udev: renamed network interface wlan0 to ath0
ath0: direct probe to AP <AP_MAC> try 1
ath0 direct probe responded
ath0: authenticate with AP <AP_MAC>
ath0: authenticated
ath0: associate with AP <AP_MAC>
ath0: RX AssocResp from <AP_MAC> (capab=0x421 status=0 aid=4)
ath0: associated
phy1: Allocated STA <AP_MAC>
phy1: Inserted STA <AP_MAC>
ath0: switched to short barker preamble (BSSID=<AP_MAC>)
ath0: switched to short slot (BSSID=<AP_MAC>)

*** Sitecom AP ***
With this one I'm able to associate only when the SSID is broadcast (with or 
without encryption). Moreover the association process isn't successful at 
first try (like for the 3com AP) and the link quality is very bad. An example 
of ping statistics is the following

629 packets transmitted, 527 received, 16% packet loss, time 711605ms
rtt min/avg/max/mdev = 6.332/6303.120/151334.339/18133.729 ms, pipe 114

and it's common to get the following error message (transmission buffer 
saturated?):

ping: sendmsg: No buffer space available

When I disable the SSID I can't associate anymore to the AP, the only debug 
messages are the following:

ath5k_pci 0000:00:0b.0: PCI INT A -> Link[LNKB] -> GSI 10 (level, low) -> IRQ 
10
ath5k_pci 0000:00:0b.0: registered as 'phy12'
phy12: Selected rate control algorithm 'minstrel'
ath5k phy12: Atheros AR5212 chip found (MAC: 0x56, PHY: 0x41)
ath5k phy12: RF5112B multiband radio found (0x36)
udev: renamed network interface wlan0 to ath0

How can I debug to provide more details (e.g. using debugfs)?

Thank you for any help,
Fabio