Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965123AbZLGWBK (ORCPT ); Mon, 7 Dec 2009 17:01:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965102AbZLGWBK (ORCPT ); Mon, 7 Dec 2009 17:01:10 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:40037 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S965068AbZLGWBI (ORCPT ); Mon, 7 Dec 2009 17:01:08 -0500 Date: Mon, 7 Dec 2009 17:01:15 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Linus Torvalds cc: Zhang Rui , "Rafael J. Wysocki" , LKML , ACPI Devel Maling List , pm list Subject: Re: [GIT PULL] PM updates for 2.6.33 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1665 Lines: 41 On Mon, 7 Dec 2009, Linus Torvalds wrote: > On Mon, 7 Dec 2009, Alan Stern wrote: > > > > It only seems that way because you didn't take into account devices > > that suspend synchronously but whose children suspend asynchronously. > > But why would I care? If somebody suspends synchronously, then that's what > he wants. It doesn't mean he wants to block unrelated devices from suspending asynchronously, merely because they happen to come earlier in the list. > > A synchronous suspend routine for a device with async child suspends > > would have to look just like your usb_node_suspend(): > > Sure. But that sounds like a "Doctor, it hurts when I do this" situation. > Don't do that. > > Make the USB host controller do its suspend asynchronously. We don't > suspend PCI bridges anyway, iirc (but I didn't actually check). And at > worst, we can make the PCI _bridges_ know about async suspends, and solve > it that way - without actually making any normal PCI drivers do it. This sounds suspiciously like pushing the problem up a level and hoping it will go away. (Sometimes that even works.) In the end it isn't a very big issue. Using one vs. two passes in dpm_suspend() is pretty unimportant. Alan Stern P.S.: In fact I planned all along to handle USB host controllers asynchronously anyway, since their resume routines contain some long delays. I was merely using them as an example. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/