Return-path: Received: from s3.sipsolutions.net ([5.9.151.49]:60669 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755340AbbA0KYk (ORCPT ); Tue, 27 Jan 2015 05:24:40 -0500 Message-ID: <1422354271.1890.62.camel@sipsolutions.net> (sfid-20150127_112501_686109_D83488D8) Subject: Re: [RFCv4 3/3] mac80211: add VHT support for IBSS From: Johannes Berg To: Janusz Dziedzic Cc: linux-wireless@vger.kernel.org Date: Tue, 27 Jan 2015 11:24:31 +0100 In-Reply-To: <1422348243-4928-3-git-send-email-janusz.dziedzic@tieto.com> (sfid-20150127_094518_689625_288E01DC) References: <1422348243-4928-1-git-send-email-janusz.dziedzic@tieto.com> <1422348243-4928-3-git-send-email-janusz.dziedzic@tieto.com> (sfid-20150127_094518_689625_288E01DC) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, 2015-01-27 at 09:44 +0100, Janusz Dziedzic wrote: > +u8 *ieee80211_ie_build_vht_oper(u8 *pos, struct ieee80211_sta_vht_cap *vht_cap, > + const struct cfg80211_chan_def *chandef) > + /* 1 stream, MCS0-7 as a min Basic VHT MCS rates */ > + vht_oper->basic_mcs_set = cpu_to_le16(0xfffc); Unless I'm mistaken in my reading of the spec, this will make any well-behaved client (i.e. not mac80211) not join this network since it supports VHT MCSes. We seem to do the same for HT: /* It seems that Basic MCS set and Supported MCS set are identical for the first 10 bytes */ memset(&ht_oper->basic_set, 0, 16); memcpy(&ht_oper->basic_set, &ht_cap->mcs, 10); but I'm not convinced it's right. It probably only works because nobody ever tested against a well-behaved non-HT client? Or perhaps there isn't even one? I for one am not really comfortable with this restriction - there's very little point in making such a restriction in IBSS since if you have it then the other node will just form its own network on the same channel and you've won nothing - only lost interoperability. johannes