Return-path: Received: from ey-out-2122.google.com ([74.125.78.27]:61562 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752330Ab0AWIX0 (ORCPT ); Sat, 23 Jan 2010 03:23:26 -0500 Received: by ey-out-2122.google.com with SMTP id d26so490496eyd.19 for ; Sat, 23 Jan 2010 00:23:25 -0800 (PST) To: Johannes Berg Cc: wey-yi.w.guy@intel.com, linux-wireless@vger.kernel.org, j@w1.fi Subject: Re: [PATCH v3 1/1] mac80211: tell driver when dtim change detected References: <1264109996-15995-1-git-send-email-wey-yi.w.guy@intel.com> <1264186981.2593.10.camel@johannes.local> From: Kalle Valo Date: Sat, 23 Jan 2010 10:23:22 +0200 In-Reply-To: <1264186981.2593.10.camel@johannes.local> (Johannes Berg's message of "Fri\, 22 Jan 2010 20\:03\:01 +0100") Message-ID: <87y6jpp6v9.fsf@purkki.valot.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: Johannes Berg writes: > However, I think it's indicative of a bigger problem. I gave it some > thought, and came to the conclusion that it previously didn't happen > because we always won the race. Let me explain. One more reason why need to receive the beacon is synchronisation to the beacon for power save. For example wl1251 and wl1271 want to receive one beacon for synchronisation purposes before some of the commands are executed. It would be really nice if mac80211 would take care of that. > First, we could go back to the original behaviour if we have just one > virtual interface. I think this is good to have. Just to keep it simple for devices like wl1251 and wl1271. > But that still leaves us with the race, we might do all three frame > exchanges within a beacon interval and still miss the beacon, we > just tend to not do that and get a beacon. > > The other solution I see is that we add a new step before or after the > direct probe step, which would just be "wait for a beacon". This would > ensure we have both probe and beacon information always ready. It would > also ensure we have both probe and beacon info for our new userspace > reporting of that. I like this. If only the bssid would be provided to the driver before the association process, both wl1251 and wl1271 would not have to worry about firmware beacon synchronisation. -- Kalle Valo