Return-path: Received: from xc.sipsolutions.net ([83.246.72.84]:41790 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752317AbYJMRdh (ORCPT ); Mon, 13 Oct 2008 13:33:37 -0400 Subject: Re: [RFC] mac80211: fix short preamble determination From: Johannes Berg To: Jouni Malinen Cc: linux-wireless , Daniel Drake , Felix Fietkau In-Reply-To: <20081013155938.GA30095@jm.kir.nu> References: <1223713593.29811.38.camel@johannes.berg> <20081013155938.GA30095@jm.kir.nu> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-LYihIeyb2nXb0VsUasKu" Date: Mon, 13 Oct 2008 19:31:50 +0200 Message-Id: <1223919110.10113.1.camel@johannes.berg> (sfid-20081013_193340_804497_F6E5B133) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: --=-LYihIeyb2nXb0VsUasKu Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, 2008-10-13 at 18:59 +0300, Jouni Malinen wrote: > > - if (ieee80211_is_data(hdr->frame_control) && > > - tx->sdata->vif.bss_conf.use_short_preamble && > > - (!tx->sta || test_sta_flags(tx->sta, WLAN_STA_SHORT_PREAMBLE))) > > + if (tx->sdata->vif.bss_conf.use_short_preamble && > > + (ieee80211_is_data(hdr->frame_control) || > > + (tx->sta && test_sta_flags(tx->sta, WLAN_STA_SHORT_PREAMBLE))) >=20 > Changing '!tx->sta ||' to 'tx->sta &&' sounds reasonable, but I'm not so > sure about the other change.. In theory, short preamble is negotiated > per STA and while we do current disable short preamble completely in the > BSS if a non-short-preamble-capable STA associates, I'm not sure whether > that would be an absolute requirement. I don't see how it cannot be -- you need stations not capable of short-preamble to correctly update their NAV, no? > As far as management frames > (e.g., Probe Response) are concerned, IEEE 802.11-2007 18.2.2.2 has an > interesting statement: "all management traffic is returned with the same > type preamble as received". I have not been able to find normative > requirement for that being the case, though. Yeah, I found that statement too, but no other information on it either, heh. Not that we can actually support that easily at all. And besides, it would be kinda weird to send probe _requests_ with short preamble to start with, since then you wouldn't find APs w/o short preamble... johannes --=-LYihIeyb2nXb0VsUasKu Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Comment: Johannes Berg (powerbook) iQIcBAABAgAGBQJI84YCAAoJEKVg1VMiehFYOTAP/0FSHPcphrRjX2gmMONphw5C kvSV5BlPg7l3EUz6s4xt0+FvxGTwayYShQiYM0mHrba6Sd6nQo0BCzwgkIWs1A1o ctOR2zkNEFU22q0IwQzPRjsbJuFOraBcKMHfwESPX0OBmN/7kv4kDIsA6KJ1B07e J+Za0/hq88ofB8k0wzwiwf+uj1AgiOiuDq2vzQlHf+4X8Pz4nhuSSqDjkxmJFBKw zTCg4e1iJkca50udllEqFy8ei5mEvjPCciQd8hbVYDQcONl+GwVIB35B1xqmr9uE M2G6hzviyQmu0L0fscy5EEr8rt8sjqOqlRQYjIvdqF3phZF7KhdTXQLzjL1Gy6Q2 DyYtmqXHLIkouwqMuNFgAGEfc3hKwof6EkDbVe2Er0EyArYIIVHIZ9/nrF4wgaTc 4EYvTzQ9iWO1TVuyyi/dJq3v9OGMLdiGFrnytIpo5wIej2sssA8wjoMIqfnGdy56 z5CQaXel6NDnWzBIxoNyhoZ8wqNhVqL6q2RzhfXfqE7dGssnJEsllxhp9VDhmxex LPZx0lvhOVWYK7eo2Nv0IWp/DhlNatVZhzLCPHKDPDOH6xtFQPP3rGbMDiBYT1Q8 QVXlpf5gyxuZbEU0yFQsn5/OpI9IPtbTueTWrbbtUTSXCK16IJ8pYc+308JdyyhA JWqYNaMWuyVz8oQW3Y3U =ZefX -----END PGP SIGNATURE----- --=-LYihIeyb2nXb0VsUasKu--