From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Stern Subject: Re: [PATCH 1/3] PM / sleep: New flag to speed up suspend-resume of suspended devices Date: Thu, 27 Feb 2014 10:02:05 -0500 (EST) Message-ID: References: <4633671.dBN1DXCk1F@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from iolanthe.rowland.org ([192.131.102.54]:42638 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752522AbaB0PCI (ORCPT ); Thu, 27 Feb 2014 10:02:08 -0500 In-Reply-To: <4633671.dBN1DXCk1F@vostro.rjw.lan> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: Linux PM list , Mika Westerberg , Aaron Lu , ACPI Devel Maling List , LKML On Thu, 27 Feb 2014, Rafael J. Wysocki wrote: > > If the child knows about the problem beforehand, it can runtime-resume > > the parent during its ->suspend. > > Well, it even should do that in those cases. We may need to deal with children > that don't do that, though. > > > > Well, if power.fast_suspend set guarantees that ->suspend_late, ->suspend_noirq, > > > ->resume_noirq, and ->resume_early will be skipped for a device, then we may > > > restrict setting it for devices whose children have it set (or that have no > > > children). Initially, that will be equivalent to setting it for leaf devices > > > only, but it might be extended over time in a natural way. > > > > Initially, maybe. > > Of course initially. > > > But it's the wrong approach in general. > > In the long run - I agree. > > > The right approach is to restrict setting fast_suspend for devices whose > > children don't mind their parent being suspended when their resume callbacks > > run -- not for devices whose children also have fast_suspend set. > > I agree, but we need to know which children are OK with the parent being > suspended. Having fast_suspend set is a good indication of that. :-) > > Of course, we may introduce a separate flag for that just fine if you prefer. > > > That's the point I've been trying to express all along. > > I see. Okay. I'll wait to see the next version. Alan Stern