[rt2x00-users] Indirect register access failed

Blaise Gassend blaise at willowgarage.com
Fri Jul 2 06:15:39 AEST 2010


Hi Antonio,

This sounds like a problem I have seen. 

My current theory is that the signal level reported by the rt2800 driver
has its sign flipped. Hence, wpa_supplicant tries the AP with the lowest
signal first. That AP has a really weak signal and is probably far. The
probe doesn't make it to the AP, and hence no response comes back.
wpa_supplicant doesn't blacklist the AP when there is a probe failure,
so it keeps retrying weak APs.

This problem probably also happens if you are letting the kernel pick an
AP, for the same reason.

Which version of wpa_supplicant are you using, or are you letting the
kernel pick the AP?

You could try explicitly connecting to an AP with a strong signal, the
connection might work fine in that case.

Blaise

You could try my hacked version of wpa_supplicant, which can be found
here:
svn co
https://code.ros.org/svn/ros-pkg/stacks/linux_networking/trunk/wpa_supplicant/wpa_supplicant@30516

Just run make in the wpa_supplicant directory, and a wpa_supplicant
binary will show up there.

On Thu, 2010-07-01 at 19:24 +0200, Antonio Quartulli wrote:
> On lun, giu 21, 2010 at 11:51:05 +0200, Antonio Quartulli wrote:
> > > > > > > > The classic time out error:
> > > > > > > > 
> > > > > > > > Jun 18 21:54:57 eagle3 kernel: [   96.206662] phy0: device no longeridle - scanning
> > > > > > > > Jun 18 21:54:58 eagle3 kernel: [   97.161141] wlan0: direct probe to 00:22:3f:03:81:dd (try 1)
> > > > > > > > Jun 18 21:54:58 eagle3 kernel: [   97.361146] wlan0: direct probe to 00:22:3f:03:81:dd (try 2)
> > > > > > > > Jun 18 21:54:58 eagle3 kernel: [   97.561100] wlan0: direct probe to 00:22:3f:03:81:dd (try 3)
> > > > > > > > Jun 18 21:54:59 eagle3 kernel: [   97.761324] wlan0: direct probe to 00:22:3f:03:81:dd timed out
> > > > > > > > Jun 18 21:54:59 eagle3 kernel: [   97.766249] phy0: device now idle
> > > > > 
> > > > > First possibility: the probe requests are not sent out at all
> > > > > Second possibility: the probe requests are sent out but not received by the AP
> > > > > 
> > > > > One way to find that out would be to sniff the wireless traffic with a second
> > > > > wireless card and check if the rt2800 card sends out probe requests and if
> > > > > the AP answers them. Do you think you can do that?
> > > > 
> Hi all!
> Sorry for writing only once aweek but in this period I'm a bit in
> trouble with the university exams :P
> 
> About the card, I did some other tests (with the actual version of
> wireless-testing) and as result I got that: the first time i was not
> able to associate to the AP and i reported the same timeout as before.
> Then i turned on wireshark and magically the device has associated, but
> in wireshark i saw A LOT of retransmission by the AP!
> I tried to use some application, like dhcp for first and then a simple
> ping and I got that every packet (dhcp offer, echo reply) is sent many
> many time..
> 
> Here you can find a log of the association scenario:
> http://www.ritirata.org/ordex/association.cap
> 
> Regards,
> 
> 






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