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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 56139C2BA19 for ; Mon, 6 Apr 2020 11:33:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1CDD62072A for ; Mon, 6 Apr 2020 11:33:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="iZU89QrF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CDD62072A 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-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=E9t9gFXAsoDCp7POoS2Uz1Nsy0E0NBAi21wG6KLfHrs=; b=iZU89QrFhydmZb YUaTPrNqtBTJga+vzQ2kNSvaY3ibN6Z4ZS5zBYQqR7kkGqUC9wPu7z47b2GeypCfGkyTiDC3Y8IKP aNyd/wPsod7no1CoTCKZiHGmyFTSnBKgZPG56KQPmjV83kamiPJI7WFa7Jw67O1AZMh3/Mrj6wOV1 L2sfyF6TtNSm/2PH3xdLVQCcqfzy+djmwIjHUYISBA948ns5qemMOoLQFyB6qebdOqmYjTVihg5aD 2p9DD8Sly6fu7DiUERvtOM+mGKcImwGSdEGKkL5KMcV8dtA/B79JDkeoqnS9vMkPA3/KSAoYInUBF 3gJCQ8XuomZTnhVMpdyA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jLQ0B-00083x-TL; Mon, 06 Apr 2020 11:33:15 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jLPzb-0007RQ-HM for linux-arm-kernel@lists.infradead.org; Mon, 06 Apr 2020 11:32:41 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AAAD630E; Mon, 6 Apr 2020 04:32:38 -0700 (PDT) Received: from red-moon.cambridge.arm.com (unknown [10.57.29.239]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D22EA3F52E; Mon, 6 Apr 2020 04:32:37 -0700 (PDT) Date: Mon, 6 Apr 2020 12:32:35 +0100 From: Lorenzo Pieralisi To: Ard Biesheuvel Subject: Re: [PATCH] arm64: iort: take _DMA methods into account for named components Message-ID: <20200406113235.GB4650@red-moon.cambridge.arm.com> References: <20200404073047.17898-1-ardb@kernel.org> <20200406110401.GA4650@red-moon.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200406_043239_626466_DCBF8525 X-CRM114-Status: GOOD ( 15.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Will Deacon , robin.murphy@arm.com, Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Apr 06, 2020 at 01:16:15PM +0200, Ard Biesheuvel wrote: > On Mon, 6 Apr 2020 at 13:04, Lorenzo Pieralisi > wrote: > > > > On Sat, Apr 04, 2020 at 09:30:47AM +0200, Ard Biesheuvel wrote: > > > Where IORT nodes for named components can describe simple DMA limits > > > expressed as the number of address bits a device can driver, _DMA methods > > > in AML can express more complex topologies, involving DMA translation in > > > particular. > > > > > > Currently, we only take this _DMA method into account if it appears on a > > > ACPI device node describing a PCIe root complex, but it is perfectly > > > acceptable to attach them to named components as well, so let's ensure > > > we take them into account in those cases too. > > > > ACPI spec v6.3, 6.2.4 _DMA: > > > > "_DMA is only defined under devices that represent buses" > > > > Sure. But ACPI0004 module devices are also bus nodes, so that > statement does not exclude named components that are defined under > such a module device. Yes. _DMA is valid only if a _CRS is present, ACPI0004 does not seem to _require_ a _CRS to be considered valid. It is an example. Better to make the _DMA definition more robust and linked to ACPI0004, for instance. > > This should probably be updated and _DMA usage clarified - we can't > > leave it open to interpretation. > > > > Clarification is always better. Yes, we should be able to get this in as an Errata, better to be clear given that it is something that will be used extensively across platforms. Thanks ! Lorenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel