Stuck interrupt when scanning for wireless networks (Athero chipset)

I'm working on getting wireless running on my Thinkpad T40 with an Atheros AR5211 a/b adapter. The ath5k module loads automatically, and the dmesg output seems to indicate that it is properly detecting the card:
% dmesg|grep ath
[ 4.767272] ath5k 0000:02:02.0: registered as 'phy0'
[ 5.042780] ath: EEPROM regdomain: 0x61
[ 5.042787] ath: EEPROM indicates we should expect a direct regpair map
[ 5.042793] ath: Country alpha2 being used: 00
[ 5.042796] ath: Regpair used: 0x61
[ 5.478542] ath5k: phy0: Atheros AR5211 chip found (MAC: 0x42, PHY: 0x30)
[ 5.478549] ath5k: phy0: RF5111 5GHz radio found (0x17)
[ 5.478553] ath5k: phy0: RF2111 2GHz radio found (0x23)
I brought the interface up using ip:
% ip link show wlan0
4: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DEFAULT group default qlen 1000
link/ether [redacted] brd ff:ff:ff:ff:ff:ff
The trouble comes when I try to scan for wireless networks. I run "sudo iw dev wlan0 scan". At this point, the system becomes very sluggish, and the load average began to monotonically increase. The scan never completes; I left it for 15-20 minutes and cut it off when the load passed 3.5. The load average did not go down after iw was killed. Checking in top, the CPU was pretty evenly split between a kworker process and ksoftirqd, even with the scan terminated.
I've searched around, and while there are all manner of problems reported with getting various wireless configurations to work, no one seems to get tripped up at the scanning phase like this. Does anyone know of diagnostics I could try (or perhaps other scan tools?) to narrow down what is actually causing the CPU to get hammered?
Last edited by Gavster (2014-01-15 02:57:56)

I got a chance to play around with this a bit more, trying wireless_tools this time:
% sudo iwlist wlan0 scan
wlan0 Failed to read scan data : Resource temporarily unavailable
As before, the load average then continues to increase until the system becomes unusable. This would lead me to believe that I have a driver or kernel issue, since that would be the commonality between the two tools.
The other interesting output is this:
% dmesg|tail
[ 280.973316] ath5k: phy0: too many interrupts, giving up for now
[ 280.989985] ath5k: phy0: too many interrupts, giving up for now
[ 281.004548] ath5k: phy0: too many interrupts, giving up for now
[ 281.019983] ath5k: phy0: too many interrupts, giving up for now
[ 281.034543] ath5k: phy0: too many interrupts, giving up for now
[ 281.049984] ath5k: phy0: too many interrupts, giving up for now
[ 281.064543] ath5k: phy0: too many interrupts, giving up for now
[ 281.079983] ath5k: phy0: too many interrupts, giving up for now
[ 281.094544] ath5k: phy0: too many interrupts, giving up for now
[ 281.109122] ath5k: phy0: too many interrupts, giving up for now
Looking at longer tails, this message repeats many many times, interspersed with:
net_ratelimit: 321 callbacks suppressed
With various values for 321. Some interrupt getting stuck would make sense for why the load average blows up, but I really don't know how to fix that ...
I verified on the ath5k site (http://wireless.kernel.org/en/users/Dri … rted_Chips) that my chip is supported:
% lspci
02:02.0 Ethernet controller: Qualcomm Atheros AR5211 Wireless Network Adapter [AR5001X 802.11ab] (rev 01)
Any tips for what might cause a stuck interrupt like that?

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Stuck interrupt when scanning for wireless networks (Athero chipset)

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