MIME-Version: 1.0
In-Reply-To: <1481093061.4092.17.camel@sipsolutions.net>
References: <94eb2c110db85c2379054172dad0@google.com> <1480948100.31788.15.camel@sipsolutions.net>
 <CAH7ZN-wcvoJLTr_zYMwpbjuvMBGwmNhuVYx-MuNU1pOPTf9HEA@mail.gmail.com> <1481093061.4092.17.camel@sipsolutions.net>
From: Dmitry Shmidt <dimitrysh@google.com>
Date: Wed, 7 Dec 2016 10:39:35 -0800
Message-ID: <CAH7ZN-wP+9AGrXFUS4RY65-RyfP-J46svBvLdytP2c=QPtiaug@mail.gmail.com> (sfid-20161207_193941_498901_016A8D48)
Subject: Re: [PATCH] RFC: Universal scan proposal
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org
Content-Type: text/plain; charset=UTF-8
Sender: linux-wireless-owner@vger.kernel.org

On Tue, Dec 6, 2016 at 10:44 PM, Johannes Berg
<johannes@sipsolutions.net> wrote:
>
>> Indeed, results are results. I just want to take care of two things:
>> 1) Memory consumption - we can clear stale scan results for
>> connection, but not for location if we are using history scan.
>
> Well eventually we also have to clear for location if we run out of
> memory, that usually means dumping them out to the host, no?

Being out of memory and consuming more memory are different
things, but I agree - maybe we don't need to worry about it.

>> 2) Use of insufficient results for connection - in case we had
>> history or hotlist scan only for very limited amount of channels,
>> then we may not have enough APs in our result for "sterling"
>> connection decision.
>
> I'm not entirely sure about this case - surely noticing "we can do
> better now" is still better than waiting for being able to make the
> perfect decision?

Maybe we can just keep flag saying that currently available results
were not received by usual full scan.

>> > > Report: none / batch / immediate
>> >
>> > Not sure I see much point in "none"??
>> >
>> > Can you define these more clearly? Do you think "batch" reporting
>> > should be like the gscan buckets? Or actually have full
>> > information?
>>
>> None - means that there is not need to report. It can be useful
>> in case of roaming scan, scheduling or hotlist scan - you didn't find
>> anything suitable - don't report that there is no scan results.
>
> But that seems more of a filtering thing, combined with "immediate" for
> anything passing the filter?

We can use this approach as well.

>> > >    Request may have priority and can be inserted into
>> > > the head of the queue.
>> > >    Types of scans:
>> > > - Normal scan
>> > > - Scheduled scan
>> > > - Hotlist (BSSID scan)
>> > > - Roaming
>> > > - AutoJoin
>> >
>> > I think somebody else said this but I didn't find it now - I think
>> > this would make more sense to define in terms of expected behaviour
>> > than use cases for each type of scan.
>>
>> I think Luca made this statement.
>
> Yeah - I just couldn't find it again on re-reading the thread :)
>
>> It is totally ok from SW point of
>> view - especially due to the fact that scan is scan. However,
>> I suspect it will be harder to handle from user experience. I mean
>> at the end wireless framework / driver / FW will convert special
>> scan type to usual scan with special params and response, but why
>> to put this burden on user?
>
> I just think it's more flexible and open-ended. The actual definition
> of the resulting parameters needs to be somewhere anyway - putting it
> into driver/firmware (vs. wifi framework or so) seems to duplicate it
> and certainly makes it harder to modify/extend in the future, no?

So, let's summarize:
Instead of creating new type of generic scan with special types,
we want to go with additional expansion of scheduled scan options and
parameters (in order not to "multiply entities"), including ability to send
new scheduled scan request without stopping previous one.

Is it Ok?

> johannes