Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753847AbcKIVj5 (ORCPT ); Wed, 9 Nov 2016 16:39:57 -0500 Received: from mout.kundenserver.de ([212.227.126.187]:57179 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751427AbcKIVjz (ORCPT ); Wed, 9 Nov 2016 16:39:55 -0500 From: Arnd Bergmann To: One Thousand Gnomes Cc: Mark Rutland , "zhichang.yuan" , catalin.marinas@arm.com, will.deacon@arm.com, robh+dt@kernel.org, bhelgaas@google.com, olof@lixom.net, linux-arm-kernel@lists.infradead.org, lorenzo.pieralisi@arm.com, linux-kernel@vger.kernel.org, linuxarm@huawei.com, devicetree@vger.kernel.org, linux-pci@vger.kernel.org, linux-serial@vger.kernel.org, minyard@acm.org, benh@kernel.crashing.org, liviu.dudau@arm.com, zourongrong@gmail.com, john.garry@huawei.com, gabriele.paoloni@huawei.com, zhichang.yuan02@gmail.com, kantyzc@163.com, xuwei5@hisilicon.com, marc.zyngier@arm.com Subject: Re: [PATCH V5 2/3] ARM64 LPC: Add missing range exception for special ISA Date: Wed, 09 Nov 2016 22:38:32 +0100 Message-ID: <5900275.i4NZvtxTcC@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-34-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <20161109135453.2e5402bd@lxorguk.ukuu.org.uk> References: <1478576829-112707-1-git-send-email-yuanzhichang@hisilicon.com> <2368890.jTbyGqYR0M@wuerfel> <20161109135453.2e5402bd@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:ZesbUVGwLuXD0ZTNSSn9A564PWZj8zcrKJdloT94VzXYpxJXxJG gKBupdsfZ8ZR5Bd1SGNQteAZwPyw95SEK2ej+GEKGso6rY+pLWGAVmrHe586IRtE/USmuuz C5k/HOayWt+RpSlh25dcUVmUHIkp84SXXEJtnZLmC5+///wQTAyMsXPKhMVn/+EmOrZXDFz /rqAhzMFH7YykhKp27nrQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:kPQyQbVrd9A=:qIEu3JwsPCgea3QLcgSiL3 Q22uqHz6b0cy1gg7dAOoxA5g0wAWTXfcVvKm8FrVC1hn/GxnYhFWa8XIqQvAepQoVvSStLAkl mVxyoO2+6VIJ1338xU9nj5GJzDY0PBdBAAIweXSlFMx/fvFuwcKuJ49y3FksxD8PkrLAm1MUp 5poGBtz+PV/6BaNrVPZceUObua38AzGBApcf1R7F4CeQPTh1SpMLbMgxBn3od4evahXr5TcJr f48dmYuc8t7hVLO+QgnEG323MGq6v+eamae41LZ2z8A3WYKREazuWTXX6DFfDrF2DrKmhAL/z bdQNsTkxxseeT+iUDjd29fHTZ5Zue6T7x9Pd5ZCZ707rNXohc/b8pMz5aCshwLd8HC5YJOM+j onOOqlAUc+zldPxFmV1n4pkzBkU1JX7nriD8SqaeLQN/pFtMCpRGcZ5ns0QjJl/IwADA8sYT7 nIbVnDUhIEvbepKlpu6BA/hOASiSR1stJQCNcnhNYL/0Ri9h5CaIaOWuwmsuPF5eMwSEdVKzJ RdTVHq/e5H+n1LERx7kGcBqs2yHqGeCGXhfEtvIESf6qy6ko50fJqxFPX8ZWHVs512LQVr1JX 88uaz/Z0SVDVJmgV7a8v4hGhkw2Ojc719DQ0pM86Fb1h9ZArhHLjB1D+tn40YaLXdMXKEnA2T bg/M09F/swYkqI3SDBv9owcYS3i/iu7W1n4FqMhNUlC2w1JLeGR9rbJIOazXQLNx6V5rPvzuh rBQcBviVB9Sbdst/ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 779 Lines: 17 On Wednesday, November 9, 2016 1:54:53 PM CET One Thousand Gnomes wrote: > > I think it is a relatively safe assumption that there is only one > > ISA bridge. A lot of old drivers hardcode PIO or memory addresses > > It's not a safe assumption for x86 at least. There are a few systems with > multiple ISA busses particularly older laptops with a docking station. But do they have multiple ISA domains? There is no real harm in supporting it, the (small) downsides I can think of are: - a few extra cycles for the lookup, from possibly walking a linked list to find the correct set of helpers and MMIO addresses - making it too general could invite more people to design hardware around the infrastructure when we really want them to stop adding stuff like this. Arnd