Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:34355 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753840Ab2GINUC (ORCPT ); Mon, 9 Jul 2012 09:20:02 -0400 Message-ID: <1341839999.4455.48.camel@jlt3.sipsolutions.net> (sfid-20120709_152010_441115_5B9EEDA7) Subject: Re: [PATCHv2] nl/cfg/mac80211: add set_mcast_rate API From: Johannes Berg To: Antonio Quartulli Cc: "John W. Linville" , linux-wireless@vger.kernel.org Date: Mon, 09 Jul 2012 15:19:59 +0200 In-Reply-To: <20120709131813.GD4488@ritirata.org> References: <1341739885-15385-1-git-send-email-ordex@autistici.org> <1341791503-12542-1-git-send-email-ordex@autistici.org> <1341839146.4455.40.camel@jlt3.sipsolutions.net> <20120709131813.GD4488@ritirata.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, 2012-07-09 at 15:18 +0200, Antonio Quartulli wrote: > > So this is kinda broken. In fact, the whole basic rate thing is broken > > it seems. > > > > The mcast rate is per band, as it should, since you could find the same > > BSSID on a 5 GHz channel and then jump to that channel if the TSF is > > higher... > > > > However, the basic rates aren't, which is wrong: the basic rates bitmap > > could be 1,2,6,9. If the driver is like most drivers, that translates to > > a bitmap of 0x33. But 0x33, for most drivers, if applied to the 5 GHz > > rates means 6,9,24,36. See why this is broken? A rate bitmap can't be > > siwtched around between bands and still make any sense. > > I see, I wrongly thought that nl80211_parse_mcast_rate() was checking if the > provided mcast_rate belongs to the basic_rate set of the band which we are now. Well, ok, don't get confused -- there's no basic rate set "of the band", it's a BSS property. > But that's wrong! nl80211_parse_mcast_rate() only checks if the provided > mcast_rate exists somewhere... It checks that each rate exists in the band that it's for. > > Oh, also, I'm not sure why you do BIT(... -1), but that's unrelated. > > What kind of value is the mcast rate? A rate index, or a number? > > > > it's an index and actually it's the index +1, as reported in mac80211.h: > > * @mcast_rate: per-band multicast rate index + 1 (0: disabled) also in the cfg80211 API? johannes