Return-path: Received: from s3.sipsolutions.net ([5.9.151.49]:38498 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753058AbaIHIx3 (ORCPT ); Mon, 8 Sep 2014 04:53:29 -0400 Message-ID: <1410166400.7983.9.camel@jlt4.sipsolutions.net> (sfid-20140908_105332_298823_1E956690) Subject: Re: [PATCH v6 2/2] mac80211: support DTPC IE (from Cisco Client eXtensions) From: Johannes Berg To: "Steinar H. Gunderson" Cc: linux-wireless@vger.kernel.org Date: Mon, 08 Sep 2014 10:53:20 +0200 In-Reply-To: (sfid-20140903_155617_247529_E6B6D8C2) References: <20140903133328.GC18933@sesse.net> (sfid-20140903_155617_247529_E6B6D8C2) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, 2014-09-03 at 06:48 -0700, Steinar H. Gunderson wrote: > Linux already supports 802.11h, where the access point can tell the > client to reduce its transmission power. However, 802.11h is only > defined for 5 GHz, where the need for this is much smaller than on > 2.4 GHz. > > Cisco has their own solution, called DTPC (Dynamic Transmit Power > Control). Cisco APs on a controller sometimes but not always send > 802.11h; they always send DTPC, even on 2.4 GHz. This patch adds support > for parsing and honoring the DTPC IE in addition to the 802.11h > element (they do not always contain the same limits, so both must > be honored); the format is not documented, but very simple. > > Tested (on top of wireless.git and on 3.16.1) against a Cisco Aironet > 1142 joined to a Cisco 2504 WLC, by setting various transmit power > levels for the given access points and observing the results. > The Wireshark 802.11 dissector agrees with the interpretation of the > element, except for negative numbers, which seem to never happen > anyway. Applied both. johannes