From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:36183 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752872Ab2LLPN2 (ORCPT ); Wed, 12 Dec 2012 10:13:28 -0500 Received: by mail-bk0-f46.google.com with SMTP id q16so432010bkw.19 for ; Wed, 12 Dec 2012 07:13:27 -0800 (PST) From: Christian Lamparter To: Solomon Peachy Subject: Re: [PATCHv2 00/21] cw1200: ST-Ericsson cw1200 wlan device driver Date: Wed, 12 Dec 2012 16:13:12 +0100 Cc: "John W. Linville" , Steev Klimaszewski , Janusz Dziedzic , Dmitry Tarnyagin , Johannes Berg , linux-wireless@vger.kernel.org References: <1330720003-15866-1-git-send-email-dmitry.tarnyagin@stericsson.com> <20120706201839.GE1879@tuxdriver.com> <20121211232311.GA9080@shaftnet.org> In-Reply-To: <20121211232311.GA9080@shaftnet.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Message-Id: <201212121613.12750.chunkeey@googlemail.com> (sfid-20121212_161331_384926_400113B9) Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wednesday, December 12, 2012 12:23:11 AM Solomon Peachy wrote: > On Fri, Jul 06, 2012 at 04:18:40PM -0400, John W. Linville wrote: > > IIRC it's because mac80211 doesn't provide a way of pre-allocating MIC > space at the tail end of the frame -- the hardware performs the work but > still needs the space in the payload. The code I'm maintaining has > workarounds for this; not the most efficient solution but I'd rather see > the code merged as-is, and then we can incrementally improve things > (perhaps by enhancing mac80211 as needed) Mac80211 already reserves at least 18 bytes tailroom [which can be allocated by a simple skb_put]. In fact p54 uses this tailroom to pass the MIC (8 bytes) + ICV (4 bytes) to the firmware. Do you need more than 18 bytes? Regards, Chr