Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753379AbaD1TKZ (ORCPT ); Mon, 28 Apr 2014 15:10:25 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:54325 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753238AbaD1TKR (ORCPT ); Mon, 28 Apr 2014 15:10:17 -0400 Message-ID: <535E9558.8010803@wwwdotorg.org> Date: Mon, 28 Apr 2014 11:52:24 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Thierry Reding , Arnd Bergmann CC: linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, kgene.kim@samsung.com, Shaik Ameer Basha , prathyush.k@samsung.com, grundler@chromium.org, joro@8bytes.org, supash.ramaswamy@linaro.org, linux-kernel@vger.kernel.org, pullip.cho@samsung.com, tomasz.figa@gmail.com, sachin.kamat@linaro.org, iommu@lists.linux-foundation.org, linux-samsung-soc@vger.kernel.org, s.nawrocki@samsung.com, a.motakis@virtualopensystems.com, Varun.Sethi@freescale.com, joshi@samsung.com, t.figa@samsung.com, rahul.sharma@samsung.com, Hiroshi Doyu , Will Deacon Subject: Re: [PATCH v12 11/31] documentation: iommu: add binding document of Exynos System MMU References: <1398584283-22846-1-git-send-email-shaik.ameer@samsung.com> <4447051.OnJtcFSqFV@wuerfel> <20140428103919.GF19455@ulmo> <6544270.ddFBoY6LMm@wuerfel> <20140428111802.GI19455@ulmo> In-Reply-To: <20140428111802.GI19455@ulmo> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/28/2014 05:18 AM, Thierry Reding wrote: > On Mon, Apr 28, 2014 at 12:56:03PM +0200, Arnd Bergmann wrote: ... >> A lot of drivers probably only support one >> master, so they can just set #iommu-cells=<0>, others might require >> IDs that do not fit into one cell. > > You mean "#iommu-cells = <1>" for devices that only require one master? > There still has to be one cell to specify which master. Unless perhaps > if they can be arbitrarily assigned. I guess even if there's a fixed > mapping that applies to one SoC generation, it might be good to still > employ a specifier and have the mapping in DT for flexibility. #iommu-cells doesn't include the phandle, so if you want the client references to be: property = <&iommu>; then that's #iommu-cells=<0>, whereas: property = <&iommu N>; is #iommu-cells=<1>. -- 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/