WLAN status update

Werner Almesberger werner at openmoko.org
Mon Jan 12 04:02:30 CET 2009

Here's a quick update on the current state of WLAN on GTA02: a major 
source of trouble used to be the "frozen" list of access points when 
roaming. I'm still investigating the underlying problem, but it also 
seems that since we now reset the WLAN module after resume (in 2.6.28),
there are fewer situations where the frozen list becomes an issue.

Regarding general reception issues, "GNUtoo" reported on IRC 
experiencing unstable associations with default settings, but that
"wmiconfig -i eth0 --power maxperf" solved the problem.

I thought --power was mainly affecting latency, so I didn't expect 
this effect. I've asked Atheros for more information on what this 
power setting really does.

Last but not least, I'll post a proof-of-concept implementation of
rfkill soon. There are still some API semantics that need to be
clarified, and there's also the question whether the rather indirect
control we have over the transmitter is indeed compatible with the 
quite narrowly defined goals for this interface. 

Last year, I mentioned that I'd like to do a trial with a system
configuration specifically set up for this purpose. You may wonder
what happened with this. The story is that, since then, it became 
clear that most issues are connected to the frozen access point list. 
I can reproduce this problem, even if it sometimes takes a while. 
(Once, I spent a day testing a change that apparently fixed
everything. Then I realized that my change didn't actually do
anything. With the placebo effect gone, the list promptly froze a
few minutes later ...) So the trial wouldn't produce information I
need at the moment, but it'll be interesting again once the frozen
list situation is a bit better under control.

- Werner

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