[OpenWrt-Devel] [PATCH] ar71xx: add support for the UniFi AP Outdoor Plus

Stefan Rompf stefan at loplof.de
Wed Mar 18 14:57:03 EDT 2015

On Dienstag, 17. März 2015 23:24:26 Sergey Ryazanov wrote:

> > Interesting enough: When stopping all wifi related software on the device
> > and creating a monitor interface, the RF filter seems to follow
> > "iwconfig channel" commands (yes it is the madwifi driver).
> How do you realized that RF filter follows "iwconfig channel" command?

When I create a monitor interface and change from channel 1 to 13; tcpdump 
really sees channel 13 traffic. When I change back, tcpdump sees traffic from 
channel 1 again. If the filter had not followed, I would have expected the 
device to be as deaf as with current OpenWRT.

Another interesting effect is that the access point is totally non responsable 
for 0.2 seconds after a channel change. This effect multiplies if you create a 
STA interface and do an "iwlist scan". Ping replies get delayed for seconds 
while the wifi is scanning and massively changing channels during the process.

I cannot remember this effect when I used madwifi the last time ages ago. May 
be this is the RF filter code busy waiting somewhere in ath_set_channel() or 

Let's see if it can be found.

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