From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756562AbZEVQEk (ORCPT ); Fri, 22 May 2009 12:04:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754323AbZEVQEe (ORCPT ); Fri, 22 May 2009 12:04:34 -0400 Received: from qw-out-2122.google.com ([74.125.92.27]:38083 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753051AbZEVQEd convert rfc822-to-8bit (ORCPT ); Fri, 22 May 2009 12:04:33 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=YAzC9Nno4kQ9495c2LRzEz7tBe+XR5AloF2d0dInwamIRA1vJ5xtCZY6yiZtt+cJKn Z1CfO8rOiV63pUT4XZSnIBHCtjpNm2JWwgJCVbsyV6AIY31mvh1+Fl6zbER3boznrojE zUaWh05ZsOwKlG2+5jFm7vSUTjT/ACYA/Hy5I= MIME-Version: 1.0 In-Reply-To: <4d34a0a70905211953r1138a554w3b7aa99770ba15e2@mail.gmail.com> References: <1241483224-7113-1-git-send-email-khilman@deeprootsystems.com> <87eiv35eg6.fsf@deeprootsystems.com> <200905060127.24777.rjw@sisk.pl> <4d34a0a70905211953r1138a554w3b7aa99770ba15e2@mail.gmail.com> From: Kim Kyuwon Date: Sat, 23 May 2009 01:04:12 +0900 Message-ID: <4d34a0a70905220904h6734a8f1y2b2cffe08b6afa8b@mail.gmail.com> Subject: Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs To: "Rafael J. Wysocki" Cc: Andrew Morton , linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Ingo Molnar , Kyungmin Park , Kevin Hilman Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? -- Kyuwon (규원)