From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mga09.intel.com ([134.134.136.24]:51722 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755050Ab2AIBBY (ORCPT ); Sun, 8 Jan 2012 20:01:24 -0500 Message-ID: <4F0A3C62.6010403@intel.com> (sfid-20120109_020128_528254_42B6029F) Date: Mon, 09 Jan 2012 09:01:22 +0800 From: "Yan, Zheng" MIME-Version: 1.0 To: Johannes Berg CC: wey-yi.w.guy@intel.com, ilw@linux.intel.com, "netdev@vger.kernel.org" , linux-wireless Subject: Re: [PATCH RFC] iwlwifi: add basic runtime PM support References: <4F065F59.2070107@intel.com> <1325843269.3330.4.camel@jlt3.sipsolutions.net> In-Reply-To: <1325843269.3330.4.camel@jlt3.sipsolutions.net> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 01/06/2012 05:47 PM, Johannes Berg wrote: > [add linux-wireless] > > On Fri, 2012-01-06 at 10:41 +0800, Yan, Zheng wrote: >> This simple patch adds open/close based runtime PM support to the iwlwifi driver. >> Namely, make the driver suspend the device after shutting down the interface and >> resume the device when activating the interface. In my test, suspending the device >> can save about 0.4 watt power. The shortcoming is that the device no longer generate >> rfkill changes interrupt. > > NACK due to that last sentence. There's no way we can live with that in > the general case -- and your patch isn't even configurable afaict. And > I'm sure polling the rfkill flag would use just as much energy. > It's configurable, runtime PM is disabled by default. > There might be some value in this in a system that doesn't have a hard > rfkill line, but that means this needs to be configurable since the > device can't know whether there's a button or not [1]. > The patch targets system that only use software rfkill Regards Yan, Zheng > johannes > > [1] actually in theory it might be possible to determine whether or not > the pin is floating or not? I doubt even that is possible with the HW we > have though >