From: Simon Wunderlich <sw@simonwunderlich.de>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Antonio Quartulli <a@unstable.cc>, linux-wireless@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mac80211: passively scan DFS channels if requested
Date: Mon, 24 Oct 2016 15:42:18 +0200
Message-ID: <3178350.ZYYEYN7rIx@prime> (sfid-20161024_154224_969876_E47D2A04)
In-Reply-To: <1477316004.4085.17.camel@sipsolutions.net>
References: <1447464560-28104-1-git-send-email-antonio@meshcoding.com> <20161024121129.GA8925@prodigo.lan> <1477316004.4085.17.camel@sipsolutions.net>
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On Monday, October 24, 2016 3:33:24 PM CEST Johannes Berg wrote:
> > > I think it would be reasonable only if the target channel is the
> > > one we are using and we have done CSA. But when scanning non-
> > > operative channels I don't think this could work.
> > 
> > this has been sleeping for a while.. :)
> > Would it make sense to rebase it and resubmit it for inclusion?
> > 
> > Given the previous discussion we could change the logic as:
> > * always passively scan DFS channels that are not usable
> > * always actively scan DFS channels that are usable (i.e. CAC was
> > performed).
> 
> Doesn't that contradict what you said above?
> 
> If we scan, don't we possibly lose our CAC result anyway, since we went
> off-channel? In FCC at least? In ETSI I think we're allowed to do that
> for a bit?

I believe going off-channel was allowed in general - in fact, some routers CAC 
all channels on boot up and then keep the "usable" state forever.

Otherwise, it would be pretty much impossible to perform CSAs to another DFS 
channel.

Cheers,
     Simon
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