From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752344AbbBKJh4 (ORCPT ); Wed, 11 Feb 2015 04:37:56 -0500 Received: from mailout1.w1.samsung.com ([210.118.77.11]:13847 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751324AbbBKJhv (ORCPT ); Wed, 11 Feb 2015 04:37:51 -0500 X-AuditID: cbfec7f4-b7f126d000001e9a-3b-54db225bb4f2 Message-id: <54DB22EA.3050507@samsung.com> Date: Wed, 11 Feb 2015 10:37:46 +0100 From: Marek Szyprowski User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-version: 1.0 To: "arnd@arndb.de" , Will Deacon , Robin Murphy , Laura Abbott Cc: Laurent Pinchart , linux-kernel@vger.kernel.org, Mitchel Humpherys , linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, Joreg Roedel , Grant Likely Subject: Re: [PATCH/RFC 0/4] Probe deferral for IOMMU DT integration References: <1423182722-16646-1-git-send-email-lauraa@codeaurora.org> <2115835102.210232.1423348884955.JavaMail.open-xchange@oxbaltgw04.schlund.de> In-reply-to: <2115835102.210232.1423348884955.JavaMail.open-xchange@oxbaltgw04.schlund.de> Content-type: text/plain; charset=utf-8; format=flowed Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrDLMWRmVeSWpSXmKPExsVy+t/xK7rRSrdDDE4+4Lb4O+kYu8X8I+dY LQ782cFosWC/tUXn7A3sFts7Z7BbTGy6w2Kx6fE1VovLu+awWaydv43N4uCHJ6wWLz+eYHHg 8XhycB6Tx5p5axg9fv+axOhxua+XyWN2x0xWjzvX9rB5bF5S7zH5xnJGj8+b5AI4o7hsUlJz MstSi/TtErgyHjyYx1rwlqvi8pwdLA2MJzi6GDk5JARMJO58eMAKYYtJXLi3nq2LkYtDSGAp o8TsJd8ZIZxPjBI7zz5kBKniFdCS2LirgxnEZhFQlZjY/ZUFxGYTMJToetvFBmKLCsRIvFvV xwxRLyjxY/I9FpBBIgKTGSX+3v4BNpVZYD+TxKeOs2BVwgIuElMXrIFaN5VR4uPDZrBRnECj rq9Yzw5iMwuYSXx5eZgVwpaX2LzmLfMERoFZSLbMQlI2C0nZAkbmVYyiqaXJBcVJ6bmGesWJ ucWleel6yfm5mxghMfRlB+PiY1aHGAU4GJV4eAMm3AwRYk0sK67MPcQowcGsJMIbIXY7RIg3 JbGyKrUoP76oNCe1+BAjEwenVAOj86tL56tZ53wvn3xBk1/9mskMlzLvk2UCn5/vsq70eP27 SWtlZliL2tyHKdKpWS9KXlw6wpaQsvwXq0et7xIzdy3tLVErs5ZtuH3q0tauh6kxC0/mO7/h 0bOV19njJ/Rx8Zrtjxw+vjLds2hSnkqJYI6V9fX+svAzPlpfmtsZGc4WnJKJNburxFKckWio xVxUnAgAJTg1J38CAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On 2015-02-07 23:41, arnd@arndb.de wrote: > Laura Abbott hat am 6. Februar 2015 um 01:31 > geschrieben: >> The requirement for this is based on a previous patch to add clock >> support to the ARM SMMU driver[2]. Once we have clock support, it's >> possible that the driver itself may need to be defered which breaks >> a bunch of assumptions about how SMMU probing is supposed to work. > > Hi Laura, > > I was hoping that we would not need this, and instead treat the iommu in > the same way as timers and SMP initialization, both > of which need to be run early at boot time but may rely on clock controllers > to be initialized first. > > Is there a specific requirement that makes this impossible here, or is your > intention to solve the problem more nicely by allowing deferred probing > over forcing the input clocks of the iommu to be early? I case of Exynos SoCs there is also a dependency on power domains (some might be disabled by the bootloader). It is convenient to use the whole device infrastructure for this although it still doesn't provide any methods of modelling the real power management dependencies. Right now I simply ignored this problem and left it for the future. I will check if this patchset helps in our case. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland