From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Yan, Zheng" Subject: Re: [PATCH RFC] iwlwifi: add basic runtime PM support Date: Mon, 09 Jan 2012 17:04:43 +0800 Message-ID: <4F0AADAB.4070608@intel.com> References: <4F065F59.2070107@intel.com> <1325843269.3330.4.camel@jlt3.sipsolutions.net> <4F0A3C62.6010403@intel.com> <1326069251.13074.360.camel@wwguy-huron> <4F0A492A.5080504@intel.com> <1326071127.13074.367.camel@wwguy-huron> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Johannes Berg , ilw@linux.intel.com, "netdev@vger.kernel.org" , linux-wireless To: "Guy, Wey-Yi" Return-path: Received: from mga14.intel.com ([143.182.124.37]:27327 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754972Ab2AIJEp (ORCPT ); Mon, 9 Jan 2012 04:04:45 -0500 In-Reply-To: <1326071127.13074.367.camel@wwguy-huron> Sender: netdev-owner@vger.kernel.org List-ID: On 01/09/2012 09:05 AM, Guy, Wey-Yi wrote: > On Mon, 2012-01-09 at 09:55 +0800, Yan, Zheng wrote: >> On 01/09/2012 08:34 AM, Guy, Wey-Yi wrote: >>> On Mon, 2012-01-09 at 09:01 +0800, Yan, Zheng wrote: >>>> 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. >>> >>> Somehow I miss it, how you configure it? >>> >> change the value of /sys/devices/.../power/control to auto to enable the runtime PM. >> (e.g echo auto > /sys/devices/pci0000:00/0000:00:1c.3/0000:02:00.0/power/control) > > I am not sure it is acceptable, how you expect user figure out the pci > space especially the NIC can be in any of the PCI slots. > >> >>>> >>>>> 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 >>> >>> How you control that? >> I can't. Our team is working on runtime PM project, the purpose of the patch is >> more or less to demonstrate how much power can be saved. >> > I understand, but unless we figure out either make rkill interrupt works > in runtime PM, or figure out the platform does not has HW RFKILL > automatically, I don't see how this patch can upstream without generate > a lot of issues and bug reports. > Thank you for the suggestion. Yan, Zheng