Problems running ath with bgscan enabled

[Alexandre "Sunny" Kovalenko]

On Sat, 2007-10-20 at 20:02 -0700, Sam Leffler wrote:
> Kevin Oberman wrote:
> > Ever since the update of the HAL and the new 802.11 code a few months
> > ago (in current), I have been having problems, especially when I was in
> > locations with multiple APs available. 
> > 
> > The problem was periodic loss of association. If I was at home where I
> > can usually only see a couple of APs, the problem would occur an
> > average of about 10 times a day with re-association in about 10 seconds,
> > sometimes less. This is annoying, but not very disruptive.
> > 
> > When away from home and in an urban location where there are several
> > APs, both the frequency of the loss of connectivity and the time to
> > re-associate increase. Last week at the NANOG meeting there were 4
> > conference b/g APs and 4 11a APS seen at all times along with the
> > hotel's tmobile and a couple of random ones. Only the two conference
> > SSIDs (nanog-arin and nanog-arin-a) were in my wpa_supplicant.conf
> > file. 
> > 
> > My bgscan interval was the default 300 and almost every 5 minutes I
> > would lose connectivity, often for over a minute. When I made the
> > association between the bgscan interval and the drop-outs, I did an
> > "ifconfig ath0 -bgscan" and things stabilized immediately. No further
> > problems. 
> > 
> > ath_hal: 0.9.20.3 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
> > ath0: <Atheros 5212> mem 0xb4000000-0xb400ffff irq 11 at device 2.0 on pci11
> > ath0: mac 5.9 phy 4.3 radio 3.6
> > 
> > This is really not acceptable for default behavior as it won't be clear
> > to many how to fix it. Is it expected or is something wrong?
> > 
> > Thanks!
> 
> There hasn't been a hal change in a long time.  bgscan works by telling
> the ap your station is in power save mode, leaving the channel briefly,
> and then returning.  I have not seen any issues with it w/ or w/o
> wpa_supplicant.
> 
> Maybe you can provide some information to help diagnose this?  I see
> nothing helpful like a log from wpa_supplicant or statistics.
> 
> 	Sam
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This is "me too" and the question. The question is: where did sysctl
dev.ath.0.debug go? I have defined ATH_DEBUG in if_ath.c and rebuilt the
module, but id did not seem to appear. I understand that log, produced
with that sysctl set to 0x00040000, would be the first thing you need to
look into the issue, so if you would nudge me in the proper direction, I
will be happy to produce it. I have two stations in my house and
experience the problem, Kevin describes, on the regular basis. Turning
off bgscan helped enormously (thank you, Kevin).

-- 
Alexandre "Sunny" Kovalenko.