From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:44457 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752677Ab3ABNxd (ORCPT ); Wed, 2 Jan 2013 08:53:33 -0500 Message-ID: <1357134823.9839.41.camel@jlt4.sipsolutions.net> (sfid-20130102_145335_540837_95A8D1FF) Subject: Re: [PATCHv5 0/8] Add DFS master ability From: Johannes Berg To: Simon Wunderlich Cc: linux-wireless@vger.kernel.org, victorg@ti.com, linville@tuxdriver.com, kgiori@qca.qualcomm.com, zefir.kurtisi@neratec.com, adrian@freebsd.org, j@w1.fi, coelho@ti.com, assaf@ti.com, igalc@ti.com, nbd@nbd.name, mathias.kretschmer@fokus.fraunhofer.de, Simon Wunderlich Date: Wed, 02 Jan 2013 14:53:43 +0100 In-Reply-To: <1355407113-27006-1-git-send-email-siwu@hrz.tu-chemnitz.de> References: <1355407113-27006-1-git-send-email-siwu@hrz.tu-chemnitz.de> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: > I'm sending this as patch to keep the versioning, although it can be > considered as RFC, I would be suprised if all single channel/single > interface aspects were considered correctly. :) :) I think we need a bit more "design review" first. To me, the open questions are: * Should switching to a DFS channel be allowed at all? How so, if radar can't be tested before? You just stop the AP instead but userspace can do that just as well. * What happens with multiple virtual interfaces? You allow a single channel context only which makes sense, but that doesn't disallow things like having a client + AP, and then the client switching away because the P2P GO it was connected to randomly decided to switch. This would break radar detection. (1) What should happen in this case? * To avoid that problem, could restrict to a single virtual interface. However, that's unlikely to be sufficient -- you'd want to still be able to implement multi-BSSID APs which then switch together etc. * That raises another interesting question -- should multiple BSSIDs on the same channel really *all* call the driver's ap_channel_switch() callback? That seems ... strange! * Do we need any software channel switch handling? Generally the biggest issue is around multi-channel channel switch behaviour I think. Any good ideas? johannes (1) Actually today it would either break the AP (channel contexts NOT supported by the driver) or disconnect the client (otherwise)