Thinkpad T61

Wlan Problems

Ubuntu Lucid / 10.04.1

I encountered some problems with my wlan and had some strange errors in dmesg:

The first problem was:

iwl3945 0000:03:00.0: Failed to get channel info for channel 100 [0]
iwl3945 0000:03:00.0: Failed to get channel info for channel 104 [0]
iwl3945 0000:03:00.0: Failed to get channel info for channel 108 [0]
iwl3945 0000:03:00.0: Failed to get channel info for channel 112 [0]

According to this opensuse bug i filed a solution in Ubuntu Bug #340418:

Add the following to a new file

vim /etc/modprobe.d/options-iwl3945.conf

and add

options iwl3945 disable_hw_scan=0

For testing purpose do

rmmod -f iwl3945 && modprobe iwl3945 disable_hw_scan=0

The second problem was:

cfg80211: Leaving channel 5170 MHz intact on phy2 - no rule found in band on Country IE
cfg80211: Leaving channel 5180 MHz intact on phy2 - no rule found in band on Country IE
cfg80211: Leaving channel 5190 MHz intact on phy2 - no rule found in band on Country IE

Look at dmesg like this:

dmesg | grep cfg | grep country

You'll see something like this

cfg80211: Calling CRDA for country: GB
cfg80211: Received country IE:

To set the right country for your card you have to install the program iw

sudo apt-get install iw

Then you can manually do

iw reg set GB

and you'll see in dmesg:

cfg80211: Regulatory domain changed to country: GB

To automate this process you can write a so called dispatcher script for network manager (according to [1] and [2]):

vim /etc/NetworkManager/dispatcher.d/01changeCRDA

and add

#!/bin/sh
INTERFACE=$1
ACTION=$2
CODE="GB" 

if [ "$ACTION" = "up" -a "$(echo $INTERFACE|grep wlan)" ];then
       iw reg set ${CODE}
fi