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_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3C4D4C433DF for ; Tue, 30 Jun 2020 13:04:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24E49206B6 for ; Tue, 30 Jun 2020 13:04:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387898AbgF3NE1 (ORCPT ); Tue, 30 Jun 2020 09:04:27 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:6787 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387492AbgF3NE1 (ORCPT ); Tue, 30 Jun 2020 09:04:27 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 27BDADEC1BEF76A390DF; Tue, 30 Jun 2020 21:04:24 +0800 (CST) Received: from [127.0.0.1] (10.174.179.33) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.487.0; Tue, 30 Jun 2020 21:04:21 +0800 Subject: Re: [PATCH v2 01/12] ACPI/IORT: Make iort_match_node_callback walk the ACPI namespace for NC To: Lorenzo Pieralisi CC: , Will Deacon , Sudeep Holla , Catalin Marinas , Robin Murphy , "Rafael J. Wysocki" , , , , , Rob Herring , Joerg Roedel , Bjorn Helgaas , Marc Zyngier , Makarand Pawagi , Diana Craciun , Laurentiu Tudor References: <20200521130008.8266-1-lorenzo.pieralisi@arm.com> <20200619082013.13661-1-lorenzo.pieralisi@arm.com> <20200619082013.13661-2-lorenzo.pieralisi@arm.com> <718cae1f-2f33-f6d9-f278-157300b73116@huawei.com> <20200629090551.GA28873@e121166-lin.cambridge.arm.com> <765078e7-b3ec-af5d-0405-7834ba0f120a@huawei.com> <20200630102454.GA17556@e121166-lin.cambridge.arm.com> From: Hanjun Guo Message-ID: <4817d766-0437-5356-a0b9-97b111d4cae2@huawei.com> Date: Tue, 30 Jun 2020 21:04:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200630102454.GA17556@e121166-lin.cambridge.arm.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.33] X-CFilter-Loop: Reflected Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 2020/6/30 18:24, Lorenzo Pieralisi wrote: > On Tue, Jun 30, 2020 at 11:06:41AM +0800, Hanjun Guo wrote: > > [...] > >>> For devices that aren't described in the DSDT - IORT translations >>> are determined by their ACPI parent device. Do you see/Have you >>> found any issue with this approach ? >> >> The spec says "Describes the IO relationships between devices >> represented in the ACPI namespace.", and in section 3.1.1.3 Named >> component node, it says: > > PCI devices aren't necessarily described in the ACPI namespace and we > still use IORT to describe them - through the RC node. > >> "Named component nodes are used to describe devices that are also >> included in the Differentiated System Description Table (DSDT). See >> [ACPI]." >> >> So from my understanding, the IORT spec for now, can only do ID >> translations for devices in the DSDT. > > I think you can read this multiple ways but this patch does not > change this concept. What changes, is applying parent's node IORT > mapping to child nodes with no associated DSDT nodes, it is the > same thing we do with PCI and the _DMA method - we could update > the wording in the specs if that clarifies but I don't think this > deliberately disregards the specifications. I agree, but it's better to update the wording of the spec. > >>>> For a platform device, if I use its parent's full path name for >>>> its named component entry, then it will match, but this will violate >>>> the IORT spec. >>> >>> Can you elaborate on this please I don't get the point you >>> are making. >> >> For example, device A is not described in DSDT so can't represent >> as a NC node in IORT. Device B can be described in DSDT and it >> is the parent of device A, so device B can be represented in IORT >> with memory access properties and node flags with Substream width >> and Stall supported info. >> >> When we trying to translate device A's ID, we reuse all the memory >> access properties and node flags from its parent (device B), but >> will it the same? > > I assume so why wouldn't it be ? Why would be describe them in > a parent-child relationship if that's not how the system looks like > in HW ? The point I'm making is that I'm not sure all the memory access and stall properties are the same for the parent and the device itself. > > Do you have a specific example in mind that we should be aware of ? > >> So the IORT spec don't support this, at least it's pretty vague >> I think. > > I think that's a matter of wording, it can be updated if it needs be, > reach out if you see any issue with the current approach please. If the all the properties for parent and device itself are the same, I have no strong opinion for this patch, but it's better to update the wording of the spec as well. Thanks Hanjun