Return-path: Received: from nbd.name ([46.4.11.11]:48236 "EHLO nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751001Ab1ITTbX (ORCPT ); Tue, 20 Sep 2011 15:31:23 -0400 Message-ID: <4E78EA05.6000005@openwrt.org> (sfid-20110920_213126_437612_5B0DB43A) Date: Tue, 20 Sep 2011 21:31:17 +0200 From: Felix Fietkau MIME-Version: 1.0 To: "Luis R. Rodriguez" CC: Johannes Berg , Javier Cardona , Alexander Simon , linux-wireless@vger.kernel.org Subject: Re: [PATCH v3 3/3] mac80211: Add HT operation modes for IBSS References: <35635039ce7d4a79dc62b19d51ccf0d5d4838112.1316297595.git.an.alexsimon@googlemail.com> <1316437459.5995.29.camel@jlt3.sipsolutions.net> <36569806.Rgjanm0GiI@alex-1> <1316521312.3953.27.camel@jlt3.sipsolutions.net> <4E78D990.3090601@openwrt.org> <4E78DF6F.3060304@openwrt.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2011-09-20 9:05 PM, Luis R. Rodriguez wrote: > On Tue, Sep 20, 2011 at 11:46 AM, Felix Fietkau wrote: >> On 2011-09-20 8:38 PM, Luis R. Rodriguez wrote: >>> >>> On Tue, Sep 20, 2011 at 11:21 AM, Felix Fietkau wrote: >>>> >>>> On 2011-09-20 8:12 PM, Luis R. Rodriguez wrote: >>>>> >>>>> On Tue, Sep 20, 2011 at 5:21 AM, Johannes Berg >>>>> wrote: >>>>>> >>>>>> On Mon, 2011-09-19 at 17:46 +0200, Alexander Simon wrote: >>>>>> That seems pretty complex too ... >>>>>> >>>>>> I don't really know. As I said, I think I'd be happy with an >>>>>> implementation that maybe doesn't fully implement everything as long >>>>>> as >>>>>> it considers the trade-offs. >>>>> >>>>> The same questions come up with HT support and 802.11s, as per Javier >>>>> this is not really well spelled out in the spec. My recommendation is >>>>> to just support for now the most simple case and let us not entangle >>>>> ourselves with the complexities of handling trying to merge different >>>>> setups. So only enable peering up for adhoc or mesh if and only if the >>>>> observed IE matches our own supported HT caps or target configuration. >>>>> If a legacy STA tries to peer up with an HT IBSS, this would simply be >>>>> rejected. We can leave off handling the change in configuration later >>>>> for userspace, but do not see this as being a requirement for >>>>> supporting HT for IBSS or Mesh. The simpler the better, so long as we >>>>> simply respect the spec. >>>> >>>> I disagree. That'll make it useless for real deployments, which are >>>> often a >>>> mix of HT and non-HT devices. >>> >>> I'm not saying to not do it at all, I'm saying to start off with basic >>> support *first* and *later* worry about the mixing. >> >> Simply sticking with the configured HT opmode is also simple, but it's a lot >> more practical. > > Just need to deal with the complexity, the complexity question is > where do we handle this, verifying it respects the standard, and > actually getting the work done. With AP mode of operation hostapd > already does all this for us so if we want to support IBSS and Mesh > without hostapd we'd need to figure out where to stuff this code. In > the long run this would need to be resolved for both IBSS and Mesh. We > can wait for all this work to get done or get a simple taste of basic > HT support for both modes by sticking to the supported HT mode based > on the observed beacons. HT capabilities are already handled properly, the main issue is handling the HT opmode. For that, the only important bit is whether we're using HT40+, HT40- or HT20. The code can easily just fall back to HT20 when the HT opmode of the peer is incompatible with the local HT opmode. - Felix