Return-path: Received: from mail-ie0-f177.google.com ([209.85.223.177]:51935 "EHLO mail-ie0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753216AbaAXVds (ORCPT ); Fri, 24 Jan 2014 16:33:48 -0500 Received: by mail-ie0-f177.google.com with SMTP id at1so3474278iec.22 for ; Fri, 24 Jan 2014 13:33:47 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1390572447.4257.43.camel@jlt4.sipsolutions.net> References: <1390570161-25041-1-git-send-email-janusz.dziedzic@tieto.com> <1390572447.4257.43.camel@jlt4.sipsolutions.net> Date: Fri, 24 Jan 2014 22:33:47 +0100 Message-ID: (sfid-20140124_223412_869932_AF17F934) Subject: Re: [PATCH] cfg80211: set preset_chandef after channel switch From: Janusz Dziedzic To: Johannes Berg Cc: Janusz Dziedzic , linux-wireless Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2014/1/24 Johannes Berg : > On Fri, 2014-01-24 at 14:29 +0100, Janusz Dziedzic wrote: >> Set preset_chandef in channel switch notification. >> In other case we will have old preset_chandef. > > Why would we care? We only keep the preset_chandef thing around because > hostapd (currently) doesn't pass the frequency to START_AP/the first > SET_BEACON, but after that this doesn't matter. And when you shut down > hostapd, and restart it, then it'll set the preset_chandef again through > explicitly setting the channel. > > So in which case would we care? Who would ever STOP_AP and then START_AP > without a new frequency? > We have test code in cfg80211 that using preset_chandef when compare chandefs when csa. And after that I see we never change preset_chandef after csa. >From other side, I could imagine case where we have two VAPs in hostapd. - first we start first VAPs (eg. channel 36 HT40+) - next we call CSA (channel 44 HT40+) - now we start second VAPs - we will get err here because of preset_chandef (36 HT40+) BR Janusz -- Janusz Dziedzic