From: Sujith Manoharan <c_manoha@qca.qualcomm.com>
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Message-ID: <20326.48447.815801.808651@gargle.gargle.HOWL> (sfid-20120319_060200_135594_1E20E7DF)
Date: Mon, 19 Mar 2012 10:29:43 +0530
To: Adrian Chadd <adrian@freebsd.org>
CC: Johannes Berg <johannes@sipsolutions.net>,
	"Manoharan, Rajkumar" <rmanohar@qca.qualcomm.com>,
	linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: mac80211 20/40 coexist
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Adrian Chadd wrote:
> Right, but for AP mode what's involved?
> 
> * Does it send out a CSA to the same channel but different operational
> mode stuff?
> * are all current aggregation sessions maintained, or are they reset
> when a CSA to the same channel is done?
> * What about stuff to do with power saving?

All of the above probably have to be handled. :)
(along with virtual interface management).

> I'm ignoring CWM for now until I've finished off these SMP TX
> aggregation bugs, then I'll sort out channel scanning and power saving
> stuff. That sets all the right "bits" for CWM (ie, being able to queue
> all the frames without flushing them, then restarting the software TX
> queue as needed.) Once that's done, CWM should be:
> 
> * signal stop TX;
> * wait for TX threads, TX completion and TX DMA to complete;
> * signal a rate control change;
> * recalculate the rate control selection for everything in the software queues;
> * restart..

You missed the MAC/PHY update based on the new channel information.
Which is where it gets tricky, since we end up doing a full reset.

Sujith