Re: [gentoo-user] Atheros WLAN loosing link

[Nagatoro]

On Saturday 26 June 2010 14.35.28 Mick wrote:
> On Friday 25 June 2010 18:52:18 Enrico Weigelt wrote:
> > Hi folks,
> >
> >
> > my Atheros wlan (builtin, internal intenna) is regularily
> > loosing link. Reproducible in various different networks.
> > At home, my wlan ap is about 2 meter away (within the room),
> > so link quality (currently 53) shouldnt be the problem.
> >
> > Does anyone know what could cause the problem ?
> >
> > # cat /proc/version
> >
> > Linux version 2.6.31-gentoo-r10 (root@×××××××××.local) \
> > (gcc version 4.3.4 (Gentoo 4.3.4 p1.0, pie-10.1.5) ) 	\
> > #1 SMP Wed Jun 2 00:51:13 CEST 2010
> >
> > # lspci -v
> > ...
> >
> > 02:00.0 Network controller: Atheros Communications Inc. AR9285 Wireless
> > Network Adapter (PCI-Express) (rev 01) Subsystem: Askey Computer Corp.
> > Device 7167
> >
> >     Flags: bus master, fast devsel, latency 0, IRQ 16
> >     Memory at f6000000 (64-bit, non-prefetchable) [size=64K]
> >     Capabilities: [40] Power Management version 3
> >     Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit-
> >     Capabilities: [60] Express Legacy Endpoint, MSI 00
> >     Capabilities: [100] Advanced Error Reporting
> >     Capabilities: [140] Virtual Channel <?>
> >     Capabilities: [160] Device Serial Number 00-15-17-ff-ff-24-14-12
> >     Capabilities: [170] Power Budgeting <?>
> >     Kernel driver in use: ath9k
> >     Kernel modules: ath9k
> >
> > ...
> >
> >
> > Jun 25 19:36:51 excalibur kernel: wlan0: no probe response from AP
> > 00:23:08:86:d6:8f - disassociating Jun 25 19:36:51 excalibur
> > dhcpcd[10182]: wlan0: carrier lost
>
> I have seen the same problem with my internal broadcom card and of course a
> different driver.  If you check google there seem to be pages and pages of
> users reporting such a problem on different distros and with different
> makes of wireless cards.
>
> The jury's out as to what's causing this.  Is it related to modern cards
> with low power management capabilities and how this may interact with the
> kernel, or is it something to do with the tolerance built into TTL packets
> between the card and the AP?
>
> With regards to my card I have noticed that at home I stay connected for
> hours on end, at work it's a miracle if I stay online for longer than 5
> minutes (both on the same channel).  This to me says that the problem is
> one of interaction with the router, which points to tolerance on the TTL
> packets.
>
> Of course YMMV ...


Last time I had this problem I tracked it to a conflict between wpa_supplicant 
and the card driver. Basicly the card driver would send a request to assosiate 
with mac 00:00:....:00 each time a new card was found on the air and 
wpa_supplicatnt interpreted this as a request from the driver to drop the 
connection. The driver folks said that this request should be ignored and the 
wpa_supplicant folks said that this should not be ignored but instead was a 
disconnect request. Catch 22...

Because of this I had to use wep instead of wpa(2) for along time.

/Naga