On Monday, June 25, 2012 12:38:50 PM Michal Kudelski wrote:

Thus, my question is: is the function of changing the 
txpower really supported? If it is, what steps should I 
take to make it work? I tried with ifconfig up/down when I 
change the txpower, but it does not change anything. Maybe 
I do something wrong? Do I use the correct versions of the 
firmware and the driver?

No special firmware or driver is required. Just as long
as the driver supports the feature.  

I've noticed a patch related to this issue, published on 
2012-01-27 by Christian Lamparter. It seems that it is 
included in my driver version, but maybe I'm wrong and I 
should apply some additional patch?

We use NetGear WNDA3100(v1) hardware [Atheros 
AR9001U-(2)NG] and carl9170 driver 
(driverversion=3.0.0-21-generic firmware=1.9.2).

That's probably too old. The patch you are talking about
is not a -stable patch so it's not backported to 3.3.x
(or older) kernels.

So, either you can upgrade to 3.4, use compat-wireless
<http://linuxwireless.org/en/users/Download/#Getting_compat-wireless_on_Ubuntu>
or backport the patch yourself (however, this could be diffcult).

Regards,
	Christian