From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from senator.holtmann.net ([87.106.208.187]:56199 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751875Ab0EMWIS (ORCPT ); Thu, 13 May 2010 18:08:18 -0400 Subject: Re: Possible issue with mac80211 and certain access points From: Marcel Holtmann To: Chad Koehler Cc: linux-wireless@vger.kernel.org In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Fri, 14 May 2010 00:07:40 +0200 Message-ID: <1273788460.375.76.camel@localhost.localdomain> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi Chad, > Recently purchased a Palm Pre and immediately found some issues with > connecting to the Wifi Hotspot. Connecting to other access points > would work flawlessly. > > Using the Palm Pre hotspot, I can get connected, but the connection > will drop after a very short period of time. There are messages in > the system log whenever the connection drops: > > No probe response from AP
after 500ms, disconnecting. > > An internet search turned up several results for people with the same > issue, different wireless drivers and different access point types. > > I traced this message down to mac80211/mlme.c, to the > ieee80211_sta_work() function, and was able to determine that for some > reason this particular AP was not responding to probe requests. This > let me further on to the function ieee80211_mgd_probe_ap_send(), which > sends a direct probe request to the AP -- this probe request was being > sent and never responded to. > > If I change this function to send a probe request to the broadcast > address, in a similar manner to what is done in > ieee80211_direct_probe(), then the access point responds and works > without issue. > > Due to the volume of issues on the internet that I see with the same > underlying symptoms, I wonder if there are some small amount of access > points that will not respond to a direct packet probe request even > when associated. > > I admittedly know very little about wireless networking internals, so > I am hesitant to state that this fix is necessary or appropriate, but > it does solve the issue for me and I am able to remain connected to > the Palm Pre hotspot, as well as other access points that I have > tried. > > Please let me know if I can provide further information in this space. actually I ran into the same issue two days ago and was going to post it. So what I am seeing with the Palm Pre is that when we actually scan while connected to the Palm Pre, a second later we end up disconnected. Regards Marcel