Message-ID: <1390478961.4142.12.camel@jlt4.sipsolutions.net> (sfid-20140123_130930_498582_8DF207AD)
Subject: Re: [PATCH 5/7] mac80211: improve CSA locking
From: Johannes Berg <johannes@sipsolutions.net>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: Luca Coelho <luca@coelho.fi>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"Otcheretianski, Andrei" <andrei.otcheretianski@intel.com>
Date: Thu, 23 Jan 2014 13:09:21 +0100
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On Thu, 2014-01-23 at 08:57 +0100, Michal Kazior wrote:

> This is actually the tricky part. How do you automatically switch an
> AP interface? You should be able to at least generate CSA IE - true -
> but what about beacon after CSA? You need to update HT IE and VHT IE
> at least.
> 
> Perhaps we could split CSA into two parts somehow and make it more
> userspace coordinated. The first part of CSA - announcing it, is
> trivial and can actually be done entirely within mac80211 if I'm not
> mistaken. What needs userspace input is what happens after the
> announcement. This would mean that there is a possible time gap
> between announcement being completed and the actual channel switch &
> operation resuming.

I believe that even announcing it isn't necessarily possible without
userspace involvement, particularly for things like 11ac's channel
switch wrapper IE and/or operating class changes.

johannes