Wednesday, 22 February 2012

fixing disabled atheros wifi after windows7 hibernation.

While I am waiting for my new computer a coworker lend me an acer-Aspire-5535 (4GB RAM AMD Turion-X2 64). This is a cheap but nice machine when using windows7 (without fancy decorations or animations) and a virtualized Ubuntu-LXDE with virtual box.

I enjoyed the machine until I hibernate it. When started up again the system the joy disapeared: the wifi was not working (the wifi button had some sporadic flashes but no network at all). I restated the machine and wifi came back without a problem. The coworker knew the problem and lived with it for more than 3 month ( a windows update created the problem ).Solution, of the owner (a typical windows person) when no wifi after hibernation: restart it. Problem, what problem? "Restart windows and it will works fine" she said to me. But I can not live without proper hibernation. It is not only the booting time, there is also  the programs' state and the 60 firefox tabs that I don't want to reload again, and the pdfs that I am reading or using as reference etc.

PROBLEM: when windows 7 suspend to ram or hibernate, it shutdown the wifi card, but then is unable to activate it after restoring.

As a linux person I am get use to ifdown;ifup for resurrecting a collapsed wifi card/driver. In the old windows XP I believe I have use a restart network but I was unable to find it in windows 7. After a lot of googleing and reading a lot of unhelpful advises 90% giving as solution to reboot the computer (have any of them understood that if you do hibernation is because you don't want to shutdown !!), I have found a solution to avoid the reboot:

# hit win-R
# type 
# at the bottom of the list you will find "WLAN AutoConfig"
# click on it an slect 'stop' wait click again and select start

This will activate again the wifi.

Also, in order to prevent this happening again, I am disabling the automatic turning off of the wifi device by the system. I went to 'control_panel'->network and sharing center->manage wireless network->adapter_properties->configure->power_management->"allow computer to turn off this device to save power" and unmark this option.

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