powersaving when interface is up but not associated

From: Johannes Berg <johannes@sipsolutions.net>
To: linux-wireless <linux-wireless@vger.kernel.org>
Cc: Marcel Holtmann <marcel@holtmann.org>,
	Kalle Valo <kalle.valo@iki.fi>,
	"Guy, Wey-Yi W" <wey-yi.w.guy@intel.com>,
	Arjan van de Ven <arjan@linux.intel.com>
Subject: powersaving when interface is up but not associated
Date: Wed, 22 Apr 2009 22:15:56 +0200	[thread overview]
Message-ID: <1240431356.30082.18.camel@johannes.local> (raw)

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Hi!

Just had this idea -- when our networking interfaces are UP, but not
actually doing anything, the RF chains consume power. This is, often,
the default state, since you'll have your wifi on due to NM wanting to
find APs, but not associated, for example when on the road. Sure, you
can manually turn it off, but...

However, it doesn't seem necessary. When we are not associated to an AP,
and there are no extra interfaces in mac80211 active like monitor
interfaces, it seems that we could very well turn off the radio while
not scanning. It would be entirely trivial for mac80211 to do this,
probably a 20 line patch or so (need some bookkeeping about why radio is
disabled so it's not just four lines).

Thoughts?

johannes

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