From: Sujith Manoharan <c_manoha@qca.qualcomm.com>
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Date: Mon, 19 Mar 2012 15:38:59 +0530
To: Johannes Berg <johannes@sipsolutions.net>
CC: Adrian Chadd <adrian@freebsd.org>,
	"Manoharan, Rajkumar" <rmanohar@qca.qualcomm.com>,
	linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: mac80211 20/40 coexist
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Johannes Berg wrote:
> > As far as ath9k/ath9k_htc is concerned, I think we have to reset/reconfigure the HW
> > when a channel switch happens, since we reprogram various MAC/PHY registers based on
> > the HT bandwidth. Both ath9k and ath9k_htc update their rate control modules
> > correctly - ath9k via the rate_update() callback and ath9k_htc using BSS_CHANGED_HT
> > in bss_info_changed().
> 
> I'm not sure ath9k_htc is behaving correctly. Ok I should say that
> differently -- it's probably behaving "correctly" wrt. whatever mac80211
> did before, but we're changing the way mac80211 behaves and I believe
> that to be (more) correct, see my other email.

Well, we do a bunch of HW configuration based on the channel bandwidth, like
TX power, program MAC/PHY registers, various calibration routines at the baseband level.
So when the bandwidth changes, doing a full HW reset is required, I think.

Sujith