Subject: RE: mac80211 20/40 coexist
From: Johannes Berg <johannes@sipsolutions.net>
To: "Manoharan, Rajkumar" <rmanohar@qca.qualcomm.com>
Cc: "Manoharan, Sujith" <c_manoha@qca.qualcomm.com>,
	linux-wireless <linux-wireless@vger.kernel.org>
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Date: Sun, 18 Mar 2012 11:19:44 +0100
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Hi,

> > Yeah that's actually an interesting point -- but we have it wrong right
> > now I think. Did you see Paul's recent patch? We really shouldn't be
> > reconfiguring the channel if all we want is to stop transmitting 40 MHz,
> > we should just update rate control only. Now for in-device rate control
> > that isn't really possible today since they can't get rate_update(), but
> > that means we should add a separate callback, I think?
> 
> Yes. I missed that. I am not sure about the new callback alone is
> sufficient. We have to issue a WMI command
> to reconfigure the rc in firmware. If so, it needs firmware changes
> also. May be Sujith is the right person to answer
> about ath9k_htc.

I'm not sure I can believe this -- surely the firmware has to have a way
of dealing with stations that can't do 40 MHz and stations that can, so
switching between the two doesn't seem like a major proposal? We also
don't currently handle the action frames for that, but it seems like we
should.

Note, however, that we're now discussing something already done --
Paul's patch already removed the channel type update when all we wanted
was update the RC.

johannes