Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:60054 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752015Ab0ETFRj (ORCPT ); Thu, 20 May 2010 01:17:39 -0400 Received: by pwi5 with SMTP id 5so1907985pwi.19 for ; Wed, 19 May 2010 22:17:39 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <201005201121.49846.br1@einfach.org> References: <20100519012528.22206.77550.stgit@tt-desk> <201005201012.12045.br1@einfach.org> <201005201121.49846.br1@einfach.org> From: "Luis R. Rodriguez" Date: Wed, 19 May 2010 22:17:19 -0700 Message-ID: Subject: Re: [ath5k-devel] [PATCH v2 13/20] cfg80211: Add nl80211 antenna configuration To: Bruno Randolf Cc: "ath5k-devel@lists.ath5k.org" , "linux-wireless@vger.kernel.org" , "linville@tuxdriver.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: >> > that's not very clear. can you give me an example? >> >> iw dev wlan0 set_tx_antenna 4 > > so you want to transmit on antenna 3. if the card has 3 antennas - > why not? None of the legacy 802.11 drivers we support have more than 2 antennas, I am also not aware of any. >> > what if there is a 'legacy' hardware with 3 or more antennas? >> >> Like what? > > i can't find an actual real world example for that, but it thought it might be > possible, from what i know from the atheros eeprom which seems to be prepared > for up to 6 antennas. That's for 802.11n, I think it'd be much cleaner to treat that separately. But -- I can think of using an 802.11n device in legacy mode of operation using specific antennas.... so there's your example of a valid case for this. >> > i don't see how "my" API is too complicated, and i think it allows for a >> > clear configuration of these cases as well. >> > >> > your criticism seems to be based on the fact that it's not clear how to >> > handle 802.11n chainmask + antenna configuration, but this is not what >> > my patch is concerned about. let's go step by step... >> >> No no, that is my fault, I brought that up, I was hoping we could >> address it but it seems that we can't as I don't have time to think >> about this further in a unified clean API. But if its just going to be >> legacy then I don't see why we would use a large bitmap. > > i wanted it to be easily extensibe for 802.11n If we do want to address 802.11n then I say we go back to the drawing board and really think about how antennas settings work for 802.11n and consider chainmask settings. > and possibly 'legacy' with more antennas in the future. Legacy devices are dead. I don't know anyone in the industry making them, the 1 stream 802.11n devices are cheaper today, so there is no point in the market for it. > if there really are not any pre-N cards with more than > 2 antennas out there, Yup, I think this is the case :) > and we are sure we don't want to support more than 2 > antennas - well, we could save 6 bits... is it really worth it? You're right, then if you really don't mind lets think 802.11n through well then. Luis