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Message-ID: <345677d97346e1f6240105cc709fba00c6dc0c9d.camel@sipsolutions.net>
Subject: Re: [PATCH] mac80211: allow hardware scan to fall back to software
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Arend van Spriel <arend.vanspriel@broadcom.com>,
        linux-wireless@vger.kernel.org
Cc:     Sushant Kumar Mishra <sushant2k1513@gmail.com>,
        Siva Rebbagondla <siva.rebbagondla@redpinesignals.com>,
        Siva Rebbagondla <siva8118@gmail.com>,
        Sanjay Kumar Konduri <sanjay.konduri@redpinesignals.com>,
        Prameela Rani Garnepudi <prameela.j04cs@gmail.com>,
        Sushant Kumar Mishra <sushant.mishra@redpinesignals.com>
Date:   Thu, 18 Oct 2018 13:07:41 +0200
In-Reply-To: <eba7f8e3-9b51-b82b-fdf6-d440214ec653@broadcom.com> (sfid-20181018_124238_934759_EAD85A6A)
References: <20181018083547.23262-1-johannes@sipsolutions.net>
         <eba7f8e3-9b51-b82b-fdf6-d440214ec653@broadcom.com>
         (sfid-20181018_124238_934759_EAD85A6A)
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On Thu, 2018-10-18 at 12:42 +0200, Arend van Spriel wrote:
> 
> > + *	This callback is also allowed to return the special return value 1,
> > + *	this indicates that hardware scan isn't desirable right now and a
> > + *	software scan should be done instead. A driver wishing to use this
> > + *	capability must ensure its (hardware) scan capabilities aren't
> > + *	advertised as more capable than mac80211's software scan is.
> 
> Not sure what is meant by the last sentence. What does "more capable" 
> mean? What are (or where to find) the mac80211 software scan capabilities?

I was thinking in terms of the scan capabilities exposed to userspace
via nl80211. For example, mac80211 supports max 4 scan SSIDs (though
this is a soft limit, it doesn't really care later), and a maximum probe
request size. That's it though, so it doesn't support things like
NL80211_EXT_FEATURE_LOW_SPAN_SCAN, for example.

johannes