Wireless switch on Dell XT2 - strange behaviour of rfkill

Question

I have an Dell Latitude XT2 using an Intel WLAN card (lspci lists it as "Intel Corporation Ultimate N WiFi Link 5300") running Lubuntu 12.04 with recent updates. The laptop has a hardware WLAN switch.

I have problems activating the WLAN when booting with the hardware switch set to "off". The situation is a bit confusing, unfortunately.

rfkill lists two WLAN devices (though lspci only shows the Intel one). This is the situation when booting with the hardware switch set to "Off":

0: dell-wifi: Wireless LAN
    Soft blocked: yes
    Hard blocked: yes
1: dell-bluetooth: Bluetooth
    Soft blocked: yes
    Hard blocked: yes
2: phy0: Wireless LAN
    Soft blocked: yes
    Hard blocked: yes

From some tests, I conclude WLAN is only activated when both, the dell-wifi and phy0, are unblocked by soft- and hardware. But I can only unblock dell-wifi after the hardware switch is set to "on".

Procedure right from boot with hardware switch set to "Off":

• Soft-unblocking phy0 works as expected. Could be done by start-up script.
• sudo rfkill unblock 0: nothing happens. Soft block of dell-wifi not removed.
• Set the hardware switch to "on": phy0 gets its hard block removed. Still no WLAN.
• sudo rfkill unblock 0: both the soft and hard lock of dell-wifi are removed. WLAN is now active and works.
• sudo rfkill block 0: only adds the soft block as expected. WLAN goes off again.

So, in order to activate WLAN, I have to use the hardware switch and afterwards (manually) run a script - that's a bit inconvenient.

Does someone know a better solution? Maybe a daemon could help that listens to rfkill events to unblock dell-wifi after I have set the hardware switch to "on"? (sounds like another workaround)

When booting with the hardware switch set to "On", nothing is blocked neither hard nor soft.

Answer 1

There's already a daemon you can use for this purpose: udevd

You can create a rules file for it to listen to rfkill events, see this unix.stackexchange.com answer. Just adapt the script to your purpose, see below. Be aware my bash is not the best - it works, but probably cannot be considered a good example.

#!/bin/bash
#/usr/local/bin/unblock-dell-wifi

DEV_CHANGED_BY_HW_SWITCH=phy0
DEV_TO_UNBLOCK=dell-wifi


if [ ${RFKILL_NAME} != ${DEV_CHANGED_BY_HW_SWITCH} ]
then
        exit
fi


# get $DEV_TO_UNBLOCK rfkill id
DEV_TO_UNBLOCK_ID=`rfkill list wlan | grep $DEV_TO_UNBLOCK | grep -o -e "^[0-9]*"`

# maybe add error handling if $DEV_TO_UNBLOCK couldn't be found
if [ -z $DEV_TO_UNBLOCK_ID ]
then
        echo "$DEV_TO_UNBLOCK not found in rfkill list" 1>2&
        exit
fi  


if [ ${RFKILL_STATE} = 0 ]
then
        sudo rfkill block $DEV_TO_UNBLOCK_ID
else
        sudo rfkill unblock $DEV_TO_UNBLOCK_ID
fi