Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757608AbbEWBba (ORCPT ); Fri, 22 May 2015 21:31:30 -0400 Received: from mail-bn1bon0062.outbound.protection.outlook.com ([157.56.111.62]:47468 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756314AbbEWBb3 convert rfc822-to-8bit (ORCPT ); Fri, 22 May 2015 21:31:29 -0400 X-Greylist: delayed 3594 seconds by postgrey-1.27 at vger.kernel.org; Fri, 22 May 2015 21:31:28 EDT From: "Chalamarla, Tirumalesh" To: Marc Zyngier CC: "Richter, Robert" , Robert Richter , Thomas Gleixner , Jason Cooper , Tirumalesh Chalamarla , Radha Mohan Chintakuntla , "linux-kernel@vger.kernel.org" , linux-arm-kernel Subject: Re: [PATCH 1/4] arm64: gicv3: its: Encode domain number in PCI stream id Thread-Topic: [PATCH 1/4] arm64: gicv3: its: Encode domain number in PCI stream id Thread-Index: AQHQheK4tc4uv6mdU0aQcYS8qjQPyJ2E4HkAgAAKSYCAAtt0gIAA82wA Date: Fri, 22 May 2015 22:57:40 +0000 Message-ID: <34113ADB-C279-4AE6-A303-3328831CCD26@caviumnetworks.com> References: <1430686172-18222-1-git-send-email-rric@kernel.org> <1430686172-18222-2-git-send-email-rric@kernel.org> <20150520131138.2c94a32a@why.wild-wind.fr.eu.org> <20150520124827.GF10428@rric.localhost> <555EE831.2020503@arm.com> In-Reply-To: <555EE831.2020503@arm.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Tirumalesh.Chalamarla@caviumnetworks.com; x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [64.2.3.194] x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:BLUPR0701MB803; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:; x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(601004)(5005006)(520002)(3002001);SRVR:BLUPR0701MB803;BCL:0;PCL:0;RULEID:;SRVR:BLUPR0701MB803; x-forefront-prvs: 058441C12A x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(6009001)(479174004)(189002)(199003)(51704005)(164054003)(24454002)(377454003)(33656002)(106356001)(106116001)(5001830100001)(5001860100001)(19580395003)(36756003)(82746002)(19580405001)(122556002)(2656002)(46102003)(87936001)(92566002)(86362001)(93886004)(2950100001)(4001540100001)(101416001)(81156007)(83716003)(99286002)(5001960100002)(66066001)(105586002)(62966003)(102836002)(2900100001)(110136002)(68736005)(97736004)(40100003)(50986999)(54356999)(77156002)(76176999)(189998001)(64706001)(104396002);DIR:OUT;SFP:1101;SCL:1;SRVR:BLUPR0701MB803;H:BLUPR0701MB1780.namprd07.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; Content-Type: text/plain; charset="Windows-1252" Content-ID: <9F25879C8806DC4EBEEFEC1D6955A1F3@namprd07.prod.outlook.com> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-OriginatorOrg: caviumnetworks.com X-MS-Exchange-CrossTenant-originalarrivaltime: 22 May 2015 22:57:40.9021 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 711e4ccf-2e9b-4bcf-a551-4094005b6194 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BLUPR0701MB803 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2950 Lines: 72 > On May 22, 2015, at 1:26 AM, Marc Zyngier wrote: > > On 20/05/15 13:48, Robert Richter wrote: >> Mark, >> >> thanks for review, also of the other patches of this series. >> >> See below >> >> On 20.05.15 13:11:38, Marc Zyngier wrote: >>>> - dev_alias->dev_id = alias; >>>> + dev_alias->dev_id = (pci_domain_nr(pdev->bus) << 16) | alias; >> >>> This feels very scary. We're now assuming that the domain number will >>> always be presented to the doorbell. What guarantee do we have that >>> this is always the case, irrespective of the platform? >>> >>> Also, domains have no PCI reality, they are a Linux thing. And they can >>> be "randomly" assigned, unless you force the domain in DT with a >>> linux,pci-domain property. This looks even more wrong, specially >>> considering ACPI. >> >> The main problem here is that device ids (32 bits) are system >> specific. Since we have more than one PCI root complex we need the >> upper 16 bits in the devid for mapping. Using pci_domain_nr for this >> fits our needs for now and shouldn't affect systems with a single RC >> only as the domain nr is zero then. >> >> The domain number is incremented during initialization beginnig with >> zero and the order of it is fixed since it is taken from DT or ACPI >> tables. So we have full controll of it. I don't see issues here. > > This may match what you have on ThunderX (as long as the kernel doesn't > adopt another behaviour when allocating the domain number). But other > platforms may have a completely different numbering, which will mess > them up entirely. > >>> It really feels like we need a way to describe how the BDF numbering is >>> augmented. We also need to guarantee that we get the actual bridge >>> number, as opposed to the domain number. >> >> But true, the obove is just intermediate. In the end we need some sort >> of handler that is setup during cpu initialization that registers a >> callback for the gic to determine the device id of that paricular >> system. > > I don't really like the idea of a callback from the GIC - I'd prefer it > to be standalone, and rely on the topology information to build the > DeviceID. Mark Rutland had some ideas for DT (he posted an RFC a while > ago), maybe it would be good to get back to that and find out what we > can do. ACPI should also have similar information (IORT?). > How can some one pass this from DT, especially in GIC entry. i still think it is bus owner responsibility and call back is better idea. but if some one has a better idea for DT and ACPI, we are fine as long as it works on ThunderX. Thanks, Tirumalesh. > Thanks, > > M. > -- > Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/