Date: Sun, 17 Mar 2013 22:23:02 +0100
From: Karl Beldan <karl.beldan@gmail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Felix Fietkau <nbd@openwrt.org>, linux-wireless@vger.kernel.org
Subject: Re: [PATCH v4] mac80211/minstrel_ht: add support for using CCK rates
Message-ID: <20130317212302.GA6886@gobelin> (sfid-20130317_222317_844525_63A4910D)
References: <1360749068-3977-1-git-send-email-nbd@openwrt.org>
 <20130312094119.GA23062@magnum.frso.rivierawaves.com>
 <1363361818.8656.20.camel@jlt4.sipsolutions.net>
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On Fri, Mar 15, 2013 at 04:36:58PM +0100, Johannes Berg wrote:
> On Tue, 2013-03-12 at 10:41 +0100, Karl Beldan wrote:
> > On Wed, Feb 13, 2013 at 10:51:08AM +0100, Felix Fietkau wrote:
> > > When MCS rates start to get bad in 2.4 GHz because of long range or
> > > strong interference, CCK rates can be a lot more robust.
> > > 
> > > This patch adds a pseudo MCS group containing CCK rates (long preamble
> > > in the lower 4 slots, short preamble in the upper slots).
> > > 
> > With this, mac80211 might send CCK rates with IEEE80211_TX_CTL_AMPDU set.
> > For aggregates, if we don't currently set NO_CCK, at the very least the
> > 1st rate index should belong to an MCS_GROUP.
> 
> I guess that depends on how you expect rate control to work ... I'd
> kinda expect the driver to skip aggregation then? I think only ath9k
> even uses minstrel + aggregation?
> 

This changes the meaning of IEEE80211_TX_CTL_AMPDU.
With this there are more possible RC feedback pitfalls with the tx statuses 
IEEE80211_TX_{CTL,STAT}_AMPDU flags.
Regarding the drivers using minstrel + aggregation I can't really say, I
know ath9k runs ok with it and at work I settled for minstrel too with a
driver for our IP on a demo board.
 
Karl