From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [RFC Add in_use attribute] Let the driver know if it's in use Date: Mon, 20 Apr 2009 23:17:54 -0700 Message-ID: <20090421061754.GA20726@kroah.com> References: <20090416131323.GA16752@gandalf.sssup.it> <200904202354.04777.rjw@sisk.pl> <20090420224555.GA28697@kroah.com> <49ED54DC.6040407@gandalf.sssup.it> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <49ED54DC.6040407@gandalf.sssup.it> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Michael Trimarchi Cc: len.brown@intel.com, linux-pm@lists.linux-foundation.org, pavel@suse.cz List-Id: linux-pm@vger.kernel.org On Tue, Apr 21, 2009 at 07:08:44AM +0200, Michael Trimarchi wrote: > Hi, > > Greg KH wrote: > > On Mon, Apr 20, 2009 at 11:54:04PM +0200, Rafael J. Wysocki wrote: > > > >> On Thursday 16 April 2009, Michael Trimarchi wrote: > >> > >>> Drivers on embedded systems would be smart enough > >>> to know that some of the devices should remain powered up, because > >>> they could still be useful even when the CPU wasn't running. > >>> The patch add the in_use attribute, that it can be used by the > >>> the drivers to avoid power down during suspend. > >>> > >> OK, so the idea is that in_use will be set by the user space for devices that > >> shouldn't be suspended. Is this correct? > >> > > > > If so, why? Why would you suspend anything then? Why not just have > > userspace suspend the devices it wants to suspend and leave the ones it > > thinks is "in_use" alone? > > > > > Because it the previus thread the idea is that the driver should use > this flag > > "[linux-pm] [RFC Disable suspend on a > specific device] This is a little change in linux power scheme". I wasn't involved in that thread, and am not on linux-pm, care to summarize why this change is now recommended? > > Exactly, what are you trying to do that differs from > > device_for_each_child()? > > > Is device for each child use to visist the first level of the tree? Have you tried it? thanks, greg k-h