From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suravee Suthikulanit Subject: Re: [PATCH 4/4 V3] irqchip: gicv2m: Add support for multiple MSI for ARM64 GICv2m Date: Fri, 1 Aug 2014 11:19:18 -0500 Message-ID: <53DBBE06.5040307@amd.com> References: <1404947104-21345-1-git-send-email-suravee.suthikulpanit@amd.com> <1404947104-21345-5-git-send-email-suravee.suthikulpanit@amd.com> <87vbqej2rj.fsf@approximate.cambridge.arm.com> <53DBA603.9030509@amd.com> <53DBA986.90705@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53DBA986.90705@arm.com> Sender: linux-pci-owner@vger.kernel.org To: Marc Zyngier Cc: Mark Rutland , "jason@lakedaemon.net" , Pawel Moll , Catalin Marinas , Will Deacon , "tglx@linutronix.de" , "Harish.Kasiviswanathan@amd.com" , "linux-arm-kernel@lists.infradead.org" , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "devicetree@vger.kernel.org" List-Id: devicetree@vger.kernel.org On 8/1/2014 9:51 AM, Marc Zyngier wrote: > Hi Suravee, > > On 01/08/14 15:36, Suravee Suthikulanit wrote: >> On 7/30/2014 10:16 AM, Marc Zyngier wrote: >>> Why do we need this complexity at all? Is there any case where we'd want >>> to limit ourselves to a single vector for MSI? >> >> I think the ARM64 GICv2m should not be the limitation for the devices >> multiple MSI if there is no real hardware/design limitation. >> >>> arm64 is a new enough architecture so that we can expect all interrupt controllers to cope >>> with that. >> >> I am not sure if I understand this comment. >> >> We are not forcing all interrupt controllers for ARM64 to handle >> multi-MSI. They have the option to support if multi-MSI if they want >> to. I just think that we should not put the architectural limit here. > > Let me be clearer: I think we should put the burden of *not* handling > multi-MSI on interrupt controllers. Here, you're making the > architectural default to be "I don't support multi-MSI", hence having to > override global vectors and such for well behaved MSI controllers like > GICv2m and GICv3 ITS. > > Let's only support multi-MSI for the time being. If someone comes up > with a silly old MSI controller that can't deal with it, we'll address > the issue at that problem. > > Thanks, > > M. > Ok, I'm fine with that. Thanks for clarification. Suravee