From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966117AbdADI3S (ORCPT ); Wed, 4 Jan 2017 03:29:18 -0500 Received: from foss.arm.com ([217.140.101.70]:45638 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965086AbdADI3O (ORCPT ); Wed, 4 Jan 2017 03:29:14 -0500 Subject: Re: Need clarity on PCIe MSI interrupt in device tree To: valmiki , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org References: <2fea5a0c-7410-97fd-91d1-ae6a06ab1a52@gmail.com> Cc: helgaas@kernel.org, arnd@arndb.de, mark.rutland@arm.com From: Marc Zyngier Organization: ARM Ltd Message-ID: Date: Wed, 4 Jan 2017 08:29:06 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.5.1 MIME-Version: 1.0 In-Reply-To: <2fea5a0c-7410-97fd-91d1-ae6a06ab1a52@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/01/17 03:17, valmiki wrote: > Hi, > > I have confusion on MSI interrupt flags in PCIe documetation. > > MSI interrupts are edge triggered, but i see some controllers use > Ex:tegra <0 99 0x4>, here interrupt flags show 0x4 which means level > sensitive as per include/dt-bindings/interrupt-controller/irq.h. > > May i know why is it like this, why MSI depicted as level sensitive in > device tree. They are not. MSIs are *not* present in the device tree at all. What you have here is the cascade interrupt from an MSI controller to another interrupt controller (probably a GICv2), and that particular interrupt is level triggered. Which is perfectly fine if that's the signalling method between the two controllers. This doesn't in any way reflect how MSIs are signalled. Thanks, M. -- Jazz is not dead. It just smells funny...