From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pz0-f172.google.com ([209.85.222.172]:38677 "EHLO mail-pz0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978Ab0AURSa convert rfc822-to-8bit (ORCPT ); Thu, 21 Jan 2010 12:18:30 -0500 Received: by pzk2 with SMTP id 2so139735pzk.21 for ; Thu, 21 Jan 2010 09:18:29 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1263982729.14538.5.camel@johannes.local> From: "Luis R. Rodriguez" Date: Thu, 21 Jan 2010 09:18:09 -0800 Message-ID: <43e72e891001210918m45039636j3d5963e83ae360eb@mail.gmail.com> Subject: Re: [RFC] How to store HT (40MHz) support To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: Johannes Berg , "linux-wireless@vger.kernel.org" , Michael Buesch , "bcm43xx-dev@lists.berlios.de" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2010/1/21 Rafał Miłecki : > W dniu 20 stycznia 2010 11:18 użytkownik Johannes Berg > napisał: >> On Wed, 2010-01-20 at 01:06 +0100, Rafał Miłecki wrote: >>> +             phy->use_40mhz = conf_is_ht(conf); >> >> This is wrong, conf_is_ht might also be 20mhz, look at the other >> helpers. > > I tried to understand what actually is HT and after reading many > articles I have more knowledge but still I'm not 100% sure. > > AFAIU: > 1) HT means using more than 1 stream in channel (and can be on any: > 20MHz or 40MHz) No, you can have single stream HT devices. > 2) conf_is_ht(...) checks if mac80211 want us to use more than 1 > stream in channel No, conf_is_ht() tells you whether or not the current device configuration is set up to be on HT configuration. > 3) conf_is_ht40_minus(...) checks if we should use frequency below > current as additional 20MHz, so for example for channel 7 which is > 2,431->2,453 we should use additinal 20MHz in channel 3 which is > 2,411->2,433 Right it just means the secondary channel is on the lower part of the primary, ht40_plus means its above. > 4) conf_is_ht40_plus(...) checks if we should use frequency over > current as additional 20MHz, so for example for channel 3 which is > 2,411->2,433 we should use additinal 20MHz in channel 7 which is > 2,431->2,453 > > Is that correct? Almost, may want to read this: http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n I hope that helps. Luis