BBB - USB WiFi - wlan0 "Device or resource busy."

[tboy32]

I have an Alfa AWUS036H Wifi adapter connected to the BBB. If I attempt to
change the channel with

*ifconfig wlan0 down
iwconfig wlan0 channel 1*

I get

*Error for wireless request "Set Frequency" (8B04) :
SET failed on device wlan0 ; Device or resource busy.*

In the past I have been able to type

*iwlist wlan0 scan*

and it will correctly return the list of results, but now it just says

*wlan0 Interface doesn't support scanning : Device or resource busy*

I've tried this with the stock BBB I just received last week with a 3.8.11
kernel on it as well as after upgrading to 3.8.13 with the same results.
I'm using a 5v 2A power source and an FTDI serial cable. It won't connect
to a wireless network and I want to set the channel to rule out the
possibility that it's on the wrong frequency. I've tried killing processes
that I thought might be using the device with no success. It seems to be
using the rt18187 module - I've read elsewhere that the problem could be
caused by a driver issue, but I can't figure out how to correctly blacklist
modules in Angstrom to see if there is another compatible driver that would
be loaded instead. Maybe that's the wrong approach anyway, I'm not sure.
From what I've read it seems this adapter is pretty common - is there
anyone else that has had this issue? Thanks!

[t***@public.gmane.org]

Figured it out. Typing

*killall wpa_supplicant

*fixes the issue (solution found at
http://azitech.wordpress.com/2010/02/22/deauthenticating-reason3/). Turns
out I didn't need to set the channel first, but in order to do so I found I
had to specify an essid first before it would accept a set channel command.

Anyone know how to just disable wpa_supplicant from starting in the first
place?* systemctl disable* didn't do it. Right now I have a separate
service script run at boot just to kill wpa_supplicant.