Subject: Re: [RFC][RFT] fix iwlagn hw-rfkill while the interface is down
From: Dan Williams <dcbw@redhat.com>
To: Helmut Schaa <helmut.schaa@googlemail.com>
Cc: "John W. Linville" <linville@tuxdriver.com>,
	mohamed salim abbas <mabbaswireless@gmail.com>,
	linux-wireless@vger.kernel.org, tomas.winkler@intel.com,
	yi.zhu@intel.com, reinette.chatre@intel.com
In-Reply-To: <200901051556.13403.helmut.schaa@gmail.com>
References: <200812161307.07193.helmut.schaa@gmail.com>
	 <20081217202943.GB3516@tuxdriver.com>
	 <1229549485.26406.12.camel@localhost.localdomain>
	 <200901051556.13403.helmut.schaa@gmail.com>
Content-Type: text/plain
Date: Tue, 06 Jan 2009 10:59:44 -0500
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Sender: linux-wireless-owner@vger.kernel.org

On Mon, 2009-01-05 at 15:56 +0100, Helmut Schaa wrote:
> Am Mittwoch, 17. Dezember 2008 schrieb Dan Williams:
> > On Wed, 2008-12-17 at 15:29 -0500, John W. Linville wrote:
> > > On Wed, Dec 17, 2008 at 12:10:11PM -0800, mohamed salim abbas wrote:
> > > > the interrupt moved from pci_probe to mac_start for power saving. once
> > > > the interface is up the driver will read some register to know rfkill
> > > > status, if the interface in down the driver don't care to keep track
> > > > of rfkill switch. I wonder what the purpose of changing this behavior?
> > > 
> > > I think it still isn't settled in everyone's minds whether rfkill
> > > only matters if the device is "up" or if it is something that
> > > e.g. NetworkManager might want to monitor as a clue to bring the
> > > device up or down in response to rfkill changes.
> > 
> > The question is:  does NetworkManager just always keep the device 'up'
> > irregardless of whether it's supposed to be associated with anything
> > just so we can get rfkill events?
> 
> Another question is: is it worth to keep the interface up (and thus the
> firmware loaded) even if the transceiver is killed by a hardware switch?
> Wouldn't that consume even more power than just listening to rfkill
> interrupts (or polling the killswitch state in case of 3945) with no
> firmware loaded.
> 
> > I guess I'll treat rfkill the same as ethernet carrier.  If we cannot
> > rely on rfkill notifications when the device is down (we already can't,
> > since iwl3945 simply can't do it) 
> 
> I've just checked the 3945 and it is indeed possible to poll the killswitch
> state even if the firmware is not loaded. Hence 3945 could also expose
> the killswitch state while the interface is down (of course the driver would
> have to poll for that information).

Even polling the state once every 2 - 4 seconds would be perfectly
acceptable latency for me.  It doesn't have to be instantaneous, so we
can certainly trade off latency for fewer wakeups.  Care to propose a
patch?  it'll make a lot of people happy :)

Dan