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Date:      Sun, 14 Dec 2014 14:24:17 -0500
From:      David Blewett <david@dawninglight.net>
To:        freebsd-wireless@freebsd.org
Subject:   Problem with Atheros adapter (TP-LINK TL-WDN4800, AR9380)
Message-ID:  <CAFzAthbg6sc5Y_NBa5EanMK_qhBjaDEvE15mvLkSL5NzAT2BmA@mail.gmail.com>

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Hi All:

I've been having issues with a TP-LINK TL-WDN4800 PCI Express adapter [1]
that seem to have become worse since upgrading to 10.1-RELEASE. Since then,
I've had a couple of kernel panics. I use the adapter in hostapd mode as my
main WiFi access point. I would appreciate any help in making my setup more
reliable, and am open to trying to just about anything to help
troubleshoot.

The problems that I see are regular disconnections from a Macbook Pro
client. When this happens, sometimes the wifi icon says it is connected,
but I cannot actually transmit anything to the host (i.e., pings fail). The
only recourse is to turn the mbp's wifi off, then back on. This *usually*
succeeds, but sometimes does not. I also have an iPad that has similar
issues; turning wifi off and back on is usually sufficient to restore
connectivity.

This is my /etc/rc.conf:

wlans_ath0="wlan0"
create_args_wlan0="wlanmode hostap bssid"
ifconfig_wlan0="HOSTAP ssid MiddleEarth mode 11ng channel 2"

and /etc/hostapd-wlan0.conf:

interface=wlan0
debug=2
ctrl_interface=/var/run/hostapd
ctrl_interface_group=wheel
ssid=MiddleEarth
wpa=2
wpa_passphrase=xxxx
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP

I see a lot of this in the logs:

ath0: stuck beacon; resetting (bmiss count 8)

However, from what I've read these are due to channel congestion and are to
be expected. The kernel panics look like this:

Fatal trap 18: integer divide fault while in kernel mode
cpuid = 1; apic id = 11
instruction pointer = 0x20:0xffffffff8045161d
stack pointer           = 0x28:0xfffffe00e43bb760
frame pointer           = 0x28:0xfffffe00e43bb7b0
code segment        = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags    = interrupt enabled, ath0: stuck beacon; resetting
(bmiss count 8)
resume, IOPL = 0
current process     = 12 (swi4: clock)
trap number     = 18
panic: integer divide fault
cpuid = 0
KDB: stack backtrace:
#0 0xffffffff80963000 at kdb_backtrace+0x60
#1 0xffffffff80928125 at panic+0x155
#2 0xffffffff80d24f1f at trap_fatal+0x38f
#3 0xffffffff80d24b7c at trap+0x75c
#4 0xffffffff80d0a782 at calltrap+0x8
#5 0xffffffff8045b248 at ar9300_ani_poll_freebsd+0x48
#6 0xffffffff804093d6 at ath_calibrate+0xf6
#7 0xffffffff8093d557 at softclock_call_cc+0x177
#8 0xffffffff8093d994 at softclock+0x94
#9 0xffffffff808faf4b at intr_event_execute_handlers+0xab
#10 0xffffffff808fb396 at ithread_loop+0x96
#11 0xffffffff808f8b6a at fork_exit+0x9a

Here is the pciconf output:

ath0@pci0:2:0:0:    class=0x028000 card=0x3112168c chip=0x0030168c rev=0x01
hdr=0x00
    vendor     = 'Atheros Communications Inc.'
    device     = 'AR9300 Wireless LAN adaptor'
    class      = network

1. http://www.tp-link.com/lk/products/details/?model=TL-WDN4800

Thanks,

David Blewett



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