Message-ID: <1353927177.9488.27.camel@jlt4.sipsolutions.net> (sfid-20121126_115235_257672_02B851A0)
Subject: Re: [PATCH v4 1/6] nl80211/cfg80211: add radar detection
 command/event
From: Johannes Berg <johannes@sipsolutions.net>
To: Victor Goldenshtein <victorg@ti.com>
Cc: Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>,
	linux-wireless@vger.kernel.org, kgiori@qca.qualcomm.com,
	mcgrof@frijolero.org, zefir.kurtisi@neratec.com,
	adrian.chadd@gmail.com, j@w1.fi, coelho@ti.com, igalc@ti.com,
	adrian@freebsd.org, nbd@nbd.name, victorgld@gmail.com
Date: Mon, 26 Nov 2012 11:52:57 +0100
In-Reply-To: <50AB9E73.3090802@ti.com>
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On Tue, 2012-11-20 at 17:14 +0200, Victor Goldenshtein wrote:
> On 13/11/2012 20:05, Simon Wunderlich wrote:
> > On Tue, Nov 13, 2012 at 05:04:03PM +0200, Victor Goldenshtein wrote:
> >> On 05/11/2012 17:21, Johannes Berg wrote:
> >>> On Thu, 2012-11-01 at 09:54 +0200, Victor Goldenshtein wrote:
> >>>> On 22/10/2012 14:55, Johannes Berg wrote:
> >>>>>> 2. In __nl80211_set_channel() - to cover the case when the CAC was
> >>>>>> initiated on a "preset_chan" (during AP init phase) and the IF was
> >>>>>> removed before the AP was even started (local->oper_channel wasn't set yet).
> >>>>>
> >>>>> Hmm, I'm not sure I get it. How is "local->oper_channel" (a mac80211
> >>>>> variable) related to this cfg80211 code?
> >>>>
> >>>> It's not, just saying that its not set at this point.
> >>>>
> >>>>> start_ap() isn't expected to be able to succeed until CAC passed
> >>>>> successfully, but OTOH the channel isn't configured until then?
> >>>>
> >>>> right, the initial CAC performed before start_ap(), only by setting the
> >>>> channel with __nl80211_set_channel() + radar detection command.
> >>>
> >>> Hmm. Maybe then the channel should be passed to the radar detection
> >>> command instead? That way, it can be passed through, you can allocate a
> >>> channel context, etc. Much easier?
> >>
> >> We already pass the frequency in the radar detection command, the
> >> set channel operation comes during hostapd init flow regardless DFS
> >> implementation.
> >
> > Just for clarification for the API: Is the driver required to (re)set the channel
> > itself in the radar detection command, or do we expect that the channel was already
> > set via __nl80211_set_channel() (or other means) before?
> >
> > This would be important for other DFS modes like IBSS later.
> >
> 
> Already discussed this privately, still maybe someone else also interested.
> 
> The set channel operation is relevant only during initial CAC test,
> it set and re-set (if necessary - e.g. radar detected on the first
> channel) by the hostapd it self, so the driver doesn't required to set 
> the channel in the radar detection command.

Actually, it seems to me the radar detection command has to set the
channel and be tied to the channel context that way. I'd definitely
prefer that, even if you could use wdev->preset_chan it would be much
better to explicitly pass the channel.

johannes