From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9293C04EBF for ; Thu, 15 Nov 2018 11:14:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C57B21780 for ; Thu, 15 Nov 2018 11:14:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C57B21780 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387993AbeKOVVb (ORCPT ); Thu, 15 Nov 2018 16:21:31 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:60342 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725827AbeKOVVb (ORCPT ); Thu, 15 Nov 2018 16:21:31 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9B497A78; Thu, 15 Nov 2018 03:14:06 -0800 (PST) Received: from e107981-ln.cambridge.arm.com (e107981-ln.cambridge.arm.com [10.1.197.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 82A9D3F718; Thu, 15 Nov 2018 03:14:03 -0800 (PST) Date: Thu, 15 Nov 2018 11:13:56 +0000 From: Lorenzo Pieralisi To: Mika Westerberg Cc: Lukas Wunner , iommu@lists.linux-foundation.org, Joerg Roedel , David Woodhouse , Lu Baolu , Ashok Raj , Bjorn Helgaas , "Rafael J. Wysocki" , Jacob jun Pan , Andreas Noever , Michael Jamet , Yehezkel Bernat , Christian Kellner , Mario.Limonciello@dell.com, Anthony Wong , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] PCI / ACPI: Identify external PCI devices Message-ID: <20181115111356.GA599@e107981-ln.cambridge.arm.com> References: <20181112160628.86620-1-mika.westerberg@linux.intel.com> <20181112160628.86620-2-mika.westerberg@linux.intel.com> <20181112180203.lx72gjfplb6xlur7@wunner.de> <20181113105636.GB11202@e107981-ln.cambridge.arm.com> <20181113112700.GT2500@lahna.fi.intel.com> <20181113114527.GA12821@e107981-ln.cambridge.arm.com> <20181115102239.GU2500@lahna.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181115102239.GU2500@lahna.fi.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 15, 2018 at 12:22:39PM +0200, Mika Westerberg wrote: > On Tue, Nov 13, 2018 at 11:45:36AM +0000, Lorenzo Pieralisi wrote: > > On Tue, Nov 13, 2018 at 01:27:00PM +0200, Mika Westerberg wrote: > > > > [...] > > > > > > To be frank the concept (and Microsoft _DSD bindings) seems a bit vague > > > > and not thoroughly defined and I would question its detection at > > > > PCI/ACPI core level, I would hope this can be clarified at ACPI > > > > specification level, at least. > > > > > > I guess that is the way they envision to use _DSD. Instead of having > > > single UUID that covers all properties (like what we have with device > > > properties) they have one UUID per property "class". I certainly hope we > > > don't need to keep extending prp_guids[] array each time they invent > > > another "class" of properties. > > > > It is even worse than that. This is a unilateral/obscure change that > > won't be part of ACPI specifications (I guess it was easier to add a > > UUID than add this to the ACPI specifications through the AWSG) but it > > is still supposed to be applicable to ACPI PCI bindings on any > > platforms/arches; this way of adding bindings does not work and it > > has to be rectified. > > I agree. > > For the existing property "classes" such as the one here I don't think > we can do anything. There are systems already with these included in > their ACPI tables. > > I wonder if you have any objections regarding this patch? I have strong objections to the way these bindings have been forced upon everybody; if that's the way *generic* ACPI bindings are specified I wonder why there still exists an ACPI specification and related working group. I personally (but that's Bjorn and Rafael choice) think that this is not a change that belongs in PCI core, ACPI bindings are ill-defined and device tree bindings are non-existing. At the very least Microsoft should be asked to publish and discuss these bindings within the ACPI and UEFI forums. Lorenzo