From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757571AbZEVVZW (ORCPT ); Fri, 22 May 2009 17:25:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757141AbZEVVZL (ORCPT ); Fri, 22 May 2009 17:25:11 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:56119 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756944AbZEVVZK convert rfc822-to-8bit (ORCPT ); Fri, 22 May 2009 17:25:10 -0400 From: "Rafael J. Wysocki" To: Kim Kyuwon Subject: Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs Date: Fri, 22 May 2009 23:25:27 +0200 User-Agent: KMail/1.11.2 (Linux/2.6.30-rc6-rjw; KDE/4.2.3; x86_64; ; ) Cc: Andrew Morton , linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Ingo Molnar , Kyungmin Park , Kevin Hilman References: <1241483224-7113-1-git-send-email-khilman@deeprootsystems.com> <4d34a0a70905211953r1138a554w3b7aa99770ba15e2@mail.gmail.com> <4d34a0a70905220904h6734a8f1y2b2cffe08b6afa8b@mail.gmail.com> In-Reply-To: <4d34a0a70905220904h6734a8f1y2b2cffe08b6afa8b@mail.gmail.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200905222325.27950.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 22 May 2009, Kim Kyuwon wrote: > On Fri, May 22, 2009 at 11:53 AM, Kim Kyuwon wrote: > > On Wed, May 6, 2009 at 8:27 AM, Rafael J. Wysocki wrote: > >> On Wednesday 06 May 2009, Kevin Hilman wrote: > >>> Arve Hjønnevåg writes: > >>> > >>> > On Tue, May 5, 2009 at 8:52 AM, Kevin Hilman > >>> > wrote: > >>> >> Andrew Morton writes: > >>> >> > >>> >>> On Mon, 4 May 2009 17:27:04 -0700 Kevin Hilman wrote: > >>> >>> > >>> >>>> Interrupts that are flagged as wakeup sources via set_irq_wake() > >>> >>>> should not be disabled for suspend. > >>> >>>> > >>> >>> > >>> >>> Why not? > >>> >>> > >>> >> > >>> >> If an interrupt is a wakeup source, and it is disabled at the chip > >>> >> level, it will no longer generate interrupts, and thus no longer wake > >>> >> up the system. > >>> >> > >>> >> I'd be interested in hearing why wakeup interrupts should be disabled > >>> >> during suspend. > >> > >> That depends on whether or not they are used for anything else than wake-up. > >> > >>> > >>> [...] > >>> > >>> >>> > >>> >>> If this fixes some bug then please provide a description of that bug? > >>> >> > >>> >> The bug is that on TI OMAP, interrupts that are used for wakeup events > >>> >> are disabled by this code causing the system to no longer wake up. > >>> > > >>> > What do you do if the interrupt triggers right after your driver has > >>> > returned from its late suspend hook? > >>> > >>> If it's a wakeup IRQ, I assume you want it to prevent suspend. > >>> > >>> But I don't see how that can happen in the current code. IIUC, by the > >>> time your late suspend hook is run, your device IRQ is already > >>> disabled, so it won't trigger an interrupt that will be caught by > >>> check_wakeup_irqs() anyways. > >> > >> My understanding of __disable_irq() was that it didn't actually disable the > >> IRQ at the hardware level, allowing the CPU to actually receive the interrupt > >> and acknowledge it, but preventing the device driver for receiving it. Does > >> it work differently on the affected systems? > > > > Hi, Rafael. > > Sorry for bring the old issue but please let me ask you about > > suspend_device_irqs() function. > > > > __disable_irq() disables the IRQ at the hardware level in the > > following irq_chips > > > > i8259A_chip > > i8259_pic > > i8259A_chip > > bfin_internal_irqchip > > crisv10_irq_type > > crisv32_irq_type > > h8300irq_chip > > m_irq_chip > > mn10300_cpu_pic_level > > xtensa_irq_chip > > iop13xx_msi_chip > > msi_irq > > > > Because these irq_chips mask interrupts in 'disable' hook. > > > > Thus, your suspend_device_irqs() function disables all IRQs at the > > hardware level on all architectures which use irq_chips listed above > > in suspend state. > > Is this really what you wanted? > > > > If interrupt can wake up the system from suspend in some architectures > > and if disable_irq_wake is not supported in these architectures, I > > wonder if suspend_device_irqs() don't allow waking up by interrupt. > > > > Regards, > > Kyuwon > > > > I saw resume_device_irqs() is invoked after arch_suspend_enable_irqs() > in your resume code. > So in this gap between resume_device_irqs() and > arch_suspend_enable_irqs(), a few interrupts would be discarded. > i.e, a few data would be lost. > > If keypad wake up the system, first key pressed information would be lost. > If I2C, USB, SPI, UART wake up the system, first a few data would be lost. > > Did you also consider this issue? I think it would happen anyway with the old code, wouldn't it? Best, Rafael