From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [Patch v2] x86, ACPI, irq: Add a quirk to override SCI polarity for HyperV Date: Thu, 20 Aug 2015 13:13:34 +0200 (CEST) Message-ID: References: <1439963634-12006-1-git-send-email-jiang.liu@linux.intel.com> <55D42185.1000709@linux.intel.com> <55D427D3.7040103@linux.intel.com> <55D57160.40108@linux.intel.com> <55D59F6C.9050901@linux.intel.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from www.linutronix.de ([62.245.132.108]:36244 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751022AbbHTLOM (ORCPT ); Thu, 20 Aug 2015 07:14:12 -0400 In-Reply-To: <55D59F6C.9050901@linux.intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Jiang Liu Cc: "Rafael J. Wysocki" , "Rafael J . Wysocki" , Nick Meier , "Rafael J. Wysocki" , Len Brown , Pavel Machek , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, ACPI Devel Maling List , Linux Kernel Mailing List , "linux-pm@vger.kernel.org" On Thu, 20 Aug 2015, Jiang Liu wrote: > On 2015/8/20 17:15, Thomas Gleixner wrote: > > On Thu, 20 Aug 2015, Jiang Liu wrote: > >> When converting to hierarchical irqdomain, the IOAPIC > >> internal and interfaces have changed much, and seems no easy > >> way to revert cd68f6bd53cf. There may be three possible solutions > >> here: > >> 1) use quirk to correct SCI polarity, as the patch does. > >> 2) change IOAPIC interfaces to provide a special way to > >> handle SCI interrupt. > >> 3) change drivers/acpi/pci_link.c to penalize SCI IRQ so it > >> won't be used for PCI IRQ if SCI polarity conflicts with > >> PCI IRQ polarity. > > > > Stupid question. Is the SCI polarity ever the opposite of PCI > > polarity? I.e. is such a ACPI override valid at all? > Hi Thomas, > I have analyzed another system which works: > 1) SCI(IRQ9) works in level, high mode (so such an ACPI override is valid) > 2) there's a flag to detect whether system works in PIC or APIC mode. > 3) IRQ9 may be used for PCI IRQ if system works in PIC mode. Why? > 4) IRQ9 won't be used for PCI IRQ if system works in APIC mode. > Based on the above observation, I feel solution 3) may be the best one. Can you whip up a patch and test it on hyperv and maybe other machines which have that SCI override. Thanks tglx