Date: Mon, 26 Jan 2015 11:58:00 +0200
From: Jouni Malinen <j@w1.fi>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Dedy Lansky <dlansky@codeaurora.org>,
	linux-wireless@vger.kernel.org,
	Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Subject: Re: [PATCH] nl80211: add new scan flag to indicate P2P search
Message-ID: <20150126095800.GA12740@w1.fi> (sfid-20150126_105817_443020_56F17E34)
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 <1422260840.1890.9.camel@sipsolutions.net>
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On Mon, Jan 26, 2015 at 09:27:20AM +0100, Johannes Berg wrote:
> On Sun, 2015-01-25 at 14:30 +0200, Dedy Lansky wrote:
> > Scan request (NL80211_CMD_TRIGGER_SCAN) is used for triggering both scan
> > and P2P search.
> > At driver/firmware layer, scan and P2P search might be handled differently.
> > 
> > Add new scan flag to indicate P2P search. This flag can be used
> > by applications (e.g. wpa_supplicant) to explicitly request P2P search.
> 
> I think this ship has sailed many months ago -- too late, you can never
> rely on wpa_supplicant settings this flag.

I'm not sure I'd fully agree with that.. wpa_supplicant currently maps
its internal struct wpa_driver_scan_params::p2p_probe to
NL80211_ATTR_TX_NO_CCK_RATE (and also removal of CCK rates from
NL80211_ATTR_SCAN_SUPP_RATES). However, neither of these make much sense
in bands other than 2.4 GHz. There is ongoing effort in defining P2P
social channels on other bands and it would be useful to be prepared for
those with a clear nl80211 flag in scan parameters. P2P on those new
bands will require wpa_supplicant changes, so it is reasonable to assume
that a wpa_supplicant version that supports those bands will also
support this new flag.

> If you need to distinguish, you should be able to advertise P2P-Device
> supports, and then get P2P scans on the P2P-Device virtual interface.
> Could be a pure driver thing of course.

It would be unfortunate to force people to use P2P-Device for this.
 
-- 
Jouni Malinen                                            PGP id EFC895FA