From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756490AbZBCSAm (ORCPT ); Tue, 3 Feb 2009 13:00:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752409AbZBCSAe (ORCPT ); Tue, 3 Feb 2009 13:00:34 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37871 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752175AbZBCSAd (ORCPT ); Tue, 3 Feb 2009 13:00:33 -0500 Date: Tue, 3 Feb 2009 09:59:34 -0800 (PST) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: "Rafael J. Wysocki" cc: Benjamin Herrenschmidt , Linux Kernel Mailing List , Jesse Barnes , Andreas Schwab , Len Brown , Ingo Molnar Subject: Re: Reworking suspend-resume sequence (was: Re: PCI PM: Restore standard config registers of all devices early) In-Reply-To: <200902031804.26752.rjw@sisk.pl> Message-ID: References: <200901261904.n0QJ4Q9c016709@hera.kernel.org> <1233633061.16867.41.camel@pasglop> <200902031026.34093.rjw@sisk.pl> <200902031804.26752.rjw@sisk.pl> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) 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 On Tue, 3 Feb 2009, Rafael J. Wysocki wrote: > > Having reconsidered it, I think that the "loop of disable_irq()" may be > problematic due to MSI/MSI-X and devices that are put into D3 during the > "normal" suspend. That is, we shouldn't try to mask MSI/MSI-X for devices in > D3 Rafael, you seem to be confused about what "disable_irq()" does. It does not touch the driver hardware AT ALL. It literally just touches the interrupt controller, and even that only indirectly. What disable_irq() does it literally: void disable_irq_nosync(unsigned int irq) { struct irq_desc *desc = irq_to_desc(irq); unsigned long flags; if (!desc) return; spin_lock_irqsave(&desc->lock, flags); if (!desc->depth++) { desc->status |= IRQ_DISABLED; desc->chip->disable(irq); } spin_unlock_irqrestore(&desc->lock, flags); } and then it does a "synchronize_irq()" to wait to make sure that there are no pending ones. And in many cases, even the desc->chip->disable(irq); doesn't actually _do_ anything - we'll quite possibly continue to take the interrupt, and only when the interrupt happens will it see the "oh, IRQ_DISABLED is set" thing, and do something about it. So don't worry about putting devices in D3 - disable_irq() will not care AT ALL whether the device is alive or not, and will never try to touch it anyway. Linus