Message-ID: <1390386722.4334.28.camel@jlt4.sipsolutions.net> (sfid-20140122_113215_369177_D15DC93D)
Subject: Re: [PATCH 2/2] mac80211: implement multi-interface CSA
From: Johannes Berg <johannes@sipsolutions.net>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	Luca Coelho <luca@coelho.fi>
Date: Wed, 22 Jan 2014 11:32:02 +0100
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On Wed, 2014-01-22 at 11:23 +0100, Michal Kazior wrote:
> On 22 January 2014 10:58, Johannes Berg <johannes@sipsolutions.net> wrote:
> > On Wed, 2014-01-22 at 10:40 +0100, Michal Kazior wrote:
> >> > That's true, so maybe you just need to explain this chandef thing
> >> > better? I don't really see the utility (admittedly without actually
> >> > checking carefully in the code where you need it)
> >>
> >> Since you can CSA multiple interfaces you can have different chandefs
> >> for those interfaces. This means you need to know the chandef for the
> >> final channel switch.
> >>
> >> You could probably cache this to local->csa_chandef when processing
> >> the channel switch request itself, but that means you explicitly limit
> >> yourself to single CSA against a given hw/driver.
> >>
> >> At one point I was contemplating having a dedicated structure for
> >> channel switches, and have a list of channel switch structures in
> >> ieee80211_local, but perhaps that's just an overkill.
> >
> > But if we bind all interfaces against a 'pending' chanctx, then that's
> > all implicit in that chanctx calculating/binding, no?
> 
> Correct.
> 
> Hmm. How do you bind a pending chanctx? Does this mean an interface
> can have two channel contexts - the current one, and the pending one?
> 
> I suppose you'd still need to iterate over interfaces (through
> local->interfaces or the [non-existent yet] chanctx->interfaces)
> anyway for validate/sanity check if the final switch is really okay,
> and/or possibly disconnect/stop some interfaces that didn't get a
> chance to request a channel switch (I'm thinking of your STA-CSA-GO
> case).

I'll have to let Luca answer this. :)

johannes