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From: Helmut Schaa <helmut.schaa@googlemail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [RFC] Improve software scan timing
Date: Tue, 23 Feb 2010 16:33:06 +0100
Cc: linux-wireless@vger.kernel.org, Kalle Valo <kalle.valo@iki.fi>
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Am Dienstag 23 Februar 2010 schrieb Johannes Berg:
> On Tue, 2010-02-23 at 16:19 +0100, Helmut Schaa wrote:
> > Should we also consider the current listen_interval for deciding how
> > long
> > we could stay away from the operating channel? That should prevent us
> > from losing too many frames but since most drivers don't register a
> > max_listen_interval we usually end up with a listen_interval of
> > 1 which is quite short (which means only scanning one channel in a
> > row).
> >
> > Kalle, Johannes, how is the listen_interval handled in the powersave
> > code?
> > Are we only sleeping for one beacon interval or are we ignoring the
> > listen_interval currently.
>
> I figured this listen interval stuff would come back to bite us at some
> point. I don't think we should negotiate a listen interval of 1. OTOH,
> I'm not convinced that all APs would reject it with a status code of 51
> if it's too large? Or is that tested anywhere like WFA?

No idea. However for iwlwifi for example we always used a listen interval
of 20 any I never saw any associations getting rejected because of this.

So maybe we could just increase the default to something between 5 and 10
to be on the safe side?

> In any case, right now the powersave code pretty much ignores it,
> although that's not really a good plan.

Right.

Helmut