From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752265Ab2EEF7K (ORCPT ); Sat, 5 May 2012 01:59:10 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:62781 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752046Ab2EEF7I convert rfc822-to-8bit (ORCPT ); Sat, 5 May 2012 01:59:08 -0400 MIME-Version: 1.0 In-Reply-To: References: <1336119221-21146-1-git-send-email-ying.huang@intel.com> <1336119221-21146-2-git-send-email-ying.huang@intel.com> Date: Sat, 5 May 2012 13:59:07 +0800 Message-ID: Subject: Re: [RFC v2 1/5] PM, Runtime, Add power_must_be_on flag From: huang ying To: Bjorn Helgaas Cc: Huang Ying , ming.m.lin@intel.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Zheng Yan Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 5, 2012 at 3:50 AM, Bjorn Helgaas wrote: > On Fri, May 4, 2012 at 2:13 AM, Huang Ying wrote: >> --- a/include/linux/pm.h >> +++ b/include/linux/pm.h >> @@ -536,6 +536,7 @@ struct dev_pm_info { >>        unsigned int            irq_safe:1; >>        unsigned int            use_autosuspend:1; >>        unsigned int            timer_autosuspends:1; >> +       unsigned int            power_must_be_on:1; >>        enum rpm_request        request; >>        enum rpm_status         runtime_status; >>        int                     runtime_error; > > It's a little weird to just add the field, with no users.  Would it > make sense to pull out the bits of patch 5 that use this and combine > them into a single smaller patch? This patch is needed by some other subsystem too, such as ZPODD support in following patchset: https://lkml.org/lkml/2012/3/28/23 The original plan is to merge this into linux-pm.git firstly, then merge various usage of this flag into various subsystem git tree. That will make cross-tree merging a little easier. Is it possible? > But see related comments there; it > might be safer to have a function that computes this whenever you need > it instead of caching the value. This flag may be used (or calculated if implemented as a function) when device is in suspended state. Reason is as follow from the changelog of this patch. " In general, whether to put a device into power off state should be decided by the driver of the device, but for some buses, whether to put a device into power off state may be done by the parent of the device. For example, a PCIe end point device may be put into power off state by the PCIe port connected to it. " If all devices can calculate "power_must_be_on" when it is in suspended state, then this will be a design choice. Hi, Rafael, What do you think about the idea to replace .power_must_be_on with a function (maybe add a new callback in pm_ops)? Best Regards, Huang Ying