From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 28 Jan 2015 17:38:34 -0600 From: Bjorn Helgaas To: Jiang Liu Cc: "Rafael J. Wysocki" , Thomas Gleixner , Yinghai Lu , Borislav Petkov , Lv Zheng , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Len Brown , Tony Luck , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org Subject: Re: [Patch v2 20/22] x86/PCI: Refine the way to release PCI IRQ resources Message-ID: <20150128233834.GF17623@google.com> References: <1422442660-455-1-git-send-email-jiang.liu@linux.intel.com> <1422442660-455-21-git-send-email-jiang.liu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1422442660-455-21-git-send-email-jiang.liu@linux.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-ID: On Wed, Jan 28, 2015 at 06:57:38PM +0800, Jiang Liu wrote: > Some PCI device drivers assume that pci_dev->irq won't change after > calling pci_disable_device() and pci_enable_device() during suspend and > resume. > > Commit c03b3b0738a56cf283b0d05256988d5e3c8bd719 ("x86, irq, mpparse: Cosmetic: please use the conventional 12-char SHA1 as you did below. > Release IOAPIC pin when PCI device is disabled") frees PCI IRQ > resources when pci_disable_device() is called and reallocate IRQ > resources when pci_enable_device() is called again. This breaks > above assumption. So commit 3eec595235c1 ("x86, irq, PCI: Keep IRQ > assignment for PCI devices during suspend/hibernation") and > 9eabc99a635a ("x86, irq, PCI: Keep IRQ assignment for runtime power > management") fix the issue by avoiding freeing/reallocating IRQ > resources during PCI device suspend/resume. They achieve this by > checking dev.power.is_prepared and dev.power.runtime_status. > PM maintainer, Rafael, then pointed out that it's really an ugly fix > which leaking PM internal state information to IRQ subsystem.