From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752811AbaIJCBg (ORCPT ); Tue, 9 Sep 2014 22:01:36 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:10079 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751236AbaIJCBe (ORCPT ); Tue, 9 Sep 2014 22:01:34 -0400 Message-ID: <540FAFA4.1080008@huawei.com> Date: Wed, 10 Sep 2014 09:55:48 +0800 From: Yijing Wang User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Bjorn Helgaas CC: Liviu Dudau , Rob Herring , Arnd Bergmann , Rob Herring , "Jason Gunthorpe" , Benjamin Herrenschmidt , Catalin Marinas , "Will Deacon" , Russell King , linux-pci , Linus Walleij , Tanmay Inamdar , Grant Likely , Sinan Kaya , Jingoo Han , Kukjin Kim , "Suravee Suthikulanit" , linux-arch , LKML , "Device Tree ML" , LAKML , "grant.likely@linaro.org" Subject: Re: [PATCH v10 07/10] OF: Introduce helper function for getting PCI domain_nr References: <1410184472-17630-1-git-send-email-Liviu.Dudau@arm.com> <1410184472-17630-8-git-send-email-Liviu.Dudau@arm.com> <20140908145459.GO27864@e106497-lin.cambridge.arm.com> <20140908155931.GP27864@e106497-lin.cambridge.arm.com> <540E960D.7080408@huawei.com> <20140909084621.GS27864@e106497-lin.cambridge.arm.com> <540EC8CB.7010106@huawei.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.27.212] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.540FAFB2.007F,ss=1,re=0.000,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2011-05-27 18:58:46 X-Mirapoint-Loop-Id: 00588597c07062a49489c0bbfbc5ea0e Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> OK. Sorry, I have one last question, because domain will be used to calculate the address used to >> access PCI hardware config registers. So if DTS file doesn't report the domain, how do we know >> we would access the right registers when we use the auto increment domain vaule ? >> Has there a mechanism to make sure system can access the correct registers by the domain ? > > I think you're referring to config access via ECAM (PCIe r3.0, sec > 7.2.2). In that case, I don't think the domain should be used to > compute the memory-mapped configuration address. Each host bridge is > in exactly one domain, and each host bridge has an associated ECAM > area base. The address calculation uses the bus number, device > number, function number, and register number to compute an offset into > the ECAM area. > > So as long as the DT tells you the ECAM information for each host > bridge, that should be sufficient. The domain number is then just a > Linux convenience and is not tied to the platform as it is on ia64. Hi Bjorn, you are right, thanks for your detailed explanation! :) Thanks! Yijing. > > Bjorn > > . > -- Thanks! Yijing