From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755516AbbAFOA4 (ORCPT ); Tue, 6 Jan 2015 09:00:56 -0500 Received: from mout.kundenserver.de ([212.227.17.10]:53619 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755096AbbAFOAy (ORCPT ); Tue, 6 Jan 2015 09:00:54 -0500 From: Arnd Bergmann To: linaro-acpi@lists.linaro.org Cc: Catalin Marinas , Will Deacon , Lv Zheng , Rob Herring , Daniel Lezcano , Robert Moore , "linux-acpi@vger.kernel.org" , Liviu Dudau , Robert Richter , Jason Cooper , Marc Zyngier , "jcm@redhat.com" , Mark Brown , Bjorn Helgaas , "linux-arm-kernel@lists.infradead.org" , Randy Dunlap , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Olof Johansson Subject: Re: [Linaro-acpi] [PATCH v5 18/18] Documentation: ACPI for ARM64 Date: Tue, 06 Jan 2015 14:59:27 +0100 Message-ID: <3538097.dWBy3R9lty@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <20150106112000.GA8829@e104818-lin.cambridge.arm.com> References: <1413553034-20956-1-git-send-email-hanjun.guo@linaro.org> <1797489.PjmKzBFdQA@wuerfel> <20150106112000.GA8829@e104818-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:g41mXxF2rBWo7E5Aft2gYrZmCRNZSd0cwnz57Fwrd2ztc+VMfIE FeL6it2PkvgR2xAchKxH8c//WcVVYpEhghpdQ+2//kUHRsls8B0EJX+a+RxBAmsP+PgtKpV 5l8jwvC9ux3HXAJzi/mPZZDDPEaa7D/wlTwXovYu8K5nVi6KKP0V/RCVtvN9FVw5kJnKtjv ZApMh8xiQOyb2XUfpXPBg== X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 06 January 2015 11:20:01 Catalin Marinas wrote: > On Mon, Jan 05, 2015 at 08:16:30PM +0000, Arnd Bergmann wrote: > > On Monday 05 January 2015 13:13:02 Catalin Marinas wrote: > > > > since passing no DT tables to OS but > > > > acpi=force is missing is a corner case, we can do a follow up patch to > > > > fix that, does it make sense? > > > > > > Not entirely. Why would no dtb and no acpi=force be a corner case? I > > > thought this should be the default when only ACPI tables are passed, no > > > need for an additional acpi=force argument. > > > > We don't really support the case of only ACPI tables for now. The expectation > > is that you always have working DT support, at least for the next few years > > as ACPI features are ramping up, and without acpi=force it should not try > > to use ACPI at all. > > So if both DT and ACPI are present, just use DT unless acpi=force is > passed. So far I think we agree but what I want to avoid is always > mandating acpi=force even when the DT tables are missing (in the long > run). > > Now, what's preventing a vendor firmware from providing only ACPI > tables? Do we enforce it in some way (arm-acpi.txt, kernel warning etc.) > that both DT and ACPI are supported, or at least that dts files are > merged in the kernel first? We have no way of enforcing what a board vendor ships, so if they want to have ACPI-only machines for MS Windows, they just won't work by default on Linux. Once ACPI support is mature enough, we can also have a whitelist or a different default for using it automatically when no DT is present. For drivers merged upstream, I would insist that every driver merged for an ARM64 platform has a documented DT binding that is used in the driver. Arnd