Subject: Re: [PATCH v2 0/3] mac80211 suspend/resume
From: Dan Williams <dcbw@redhat.com>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: Bob Copeland <me@bobcopeland.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless@vger.kernel.org, mabbaswireless@gmail.com
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Date: Tue, 06 Jan 2009 11:45:06 -0500
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On Wed, 2008-12-24 at 08:16 +0100, Marcel Holtmann wrote:
> Hi Bob,
> 
> > > > Running pm-suspend from pm-utils directly also triggers the problem, 
> > > > so that would seem to excuse gnome-power-manager at least.
> > > 
> > > What's the status of this? Should I look into things a bit?
> > 
> > Well, I guess I should have noticed this a lot earlier, but anyway the 
> > problem was pm-utils on Fedora 10:
> > 
> > /usr/lib/pm-utils/sleep.d/55NetworkManager:
> > 
> >     suspend_nm()
> >     {
> >         # Tell NetworkManager to shut down networking
> >         dbus-send --system                         \
> >             --dest=org.freedesktop.NetworkManager  \
> >             /org/freedesktop/NetworkManager        \
> >             org.freedesktop.NetworkManager.sleep
> >     }
> > 
> > I really don't think this is necessary (g-p-m will also do it if you 
> > set the proper gconf setting.)
> 
> this should not be needed at all. I have systems running wpa_supplicant
> and not any of the pm-utils scripts messing with it. During suspend and
> later resume it indicates normally just only a new handshake with the AP
> or a disconnect if the AP got out of range.
> 
> I think Network Manager is perfectly capable of handling state changes
> from wpa_supplicant. I really do think that this hack only exists of
> some broken drivers from really old kernels or for the 0.6 version of
> Network Manager. Remember that Ubuntu's suspend/resume solution used to
> be to unload all networking drivers on suspend.

You still want to tell NM to go to sleep so it doesn't see the
disconnection from the supplicant (triggered by the driver because it
was going to sleep), and thus try to reconnect, or try a different AP.
Ideally NM would simply listen for signals from some power service such
that we wouldn't have to have this hack, but there isn't a global power
service yet on the system bus.

Furthermore, it's nice to know if we've gone to sleep or not so that we
can do some optimizations on wakeup to find APs and reconnect faster.

Dan