From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail30s.wh2.ocn.ne.jp ([125.206.180.198]:34747 "HELO mail30s.wh2.ocn.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751439Ab0G1CDi (ORCPT ); Tue, 27 Jul 2010 22:03:38 -0400 Received: from vs3012.wh2.ocn.ne.jp (125.206.180.183) by mail30s.wh2.ocn.ne.jp (RS ver 1.0.95vs) with SMTP id 4-0715682614 for ; Wed, 28 Jul 2010 11:03:36 +0900 (JST) From: Bruno Randolf To: Johannes Berg Subject: Re: [PATCH v4 1/3] cfg80211: Add nl80211 antenna configuration Date: Wed, 28 Jul 2010 11:03:44 +0900 References: <20100727094732.27186.30900.stgit@tt-desk> <20100727094759.27186.79639.stgit@tt-desk> <1280225142.19098.10.camel@jlt3.sipsolutions.net> In-Reply-To: <1280225142.19098.10.camel@jlt3.sipsolutions.net> Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org, lrodriguez@atheros.com, Felix Fietkau MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Message-Id: <201007281103.44963.br1@einfach.org> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue July 27 2010 19:05:42 you wrote: > I'm still not convinced that this is the best approach. Can you discuss > this a bit? well... i am mainly concerned about what you call "legacy" hardware at the moment, but i am trying to make the API useful for 802.11n devices as well. first, thinking only about legacy devices with 2 antennas, the three most common settings are "fixed antenna 1", "fixed antenna 2" and "antenna diversity". luis suggested to use a simple value and constants for this, but i believe that this covers only 90% of the cases, the others being antenna setups i have described (in the commit message and per email before), which use a different antenna for TX than for RX, or diversity for RX and a single fixed antenna for TX. also, while not hugely popular or common, there *is* "legacy" hardware out there which has more than two antennas (e.g.: "pre-11n RangeMax" and "large phased array switch" which were based on ath5k chipsets) and at least the atheros eeprom supports more antennas. i'm not sure about other hardware, but i think it's good to have the flexibility to support more than two antennas in the API, also since this matches with what we need for 802.11n. that's why a bitmask makes sense. honestly, i don't know too much about 802.11n, so i need the help of people who work with 802.11n to see if this is useful for them and possibly extend it, or update the documentation to make the API more clear. but i believe that if you think 'chainmask' instead of 'antenna' it should be o.k... in the end we are just talking about antennas :) for most of the users the antenna settings will just be default, but sometimes, especially in outdoor installations less antennas are present, or special setups can be desired and this API can be used to inform the HW about available antennas, wether it's 802.11n or not. bruno