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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 EE7A5C43216 for ; Mon, 9 Aug 2021 21:24:16 +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 A98D260200 for ; Mon, 9 Aug 2021 21:24:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A98D260200 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8cwFYGQlQ8Mr6s2d+cY0uGoIFKHojuVIbiajf3CxOOQ=; b=quEsSTEMJJdMYt1fnR073VlpXU WYGGBXmRBez/2Ue3HD23WUSgDZrk+nt1bBvAstxArF54YIjGmWVwCGtEHtxy+dM/WbJPqIp4DNtMJ eQjsqEhaReCzU/IArTEFBzTlM88kKRi1kO7PioaiAAiP1JdCdwTIJwWayo9s8NCVpV9Iu9YukeND2 SKFlnC71ueygpzzQVlXgg7aU5JqaqYqsCWdAlXu1VcVWLpPt3QcvwdSdGFfJY2HOICjwY0gdTwVny M3MP5H2gsf2laOR9M2+ldAPy1ypASQuk7J/B0dRomuThgLCfavNMebLgMnsF/xwdSgPXI/tPMHkcz oaVzJFkw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mDCiE-0020yu-O1; Mon, 09 Aug 2021 21:21:34 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mDCiA-0020y3-Vg; Mon, 09 Aug 2021 21:21:32 +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 2705D6D; Mon, 9 Aug 2021 14:21:26 -0700 (PDT) Received: from [192.168.122.166] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A1DEB3F40C; Mon, 9 Aug 2021 14:21:25 -0700 (PDT) Subject: Re: [PATCH 2/3] PCI: brcmstb: Add ACPI config space quirk To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, lorenzo.pieralisi@arm.com, nsaenz@kernel.org, bhelgaas@google.com, rjw@rjwysocki.net, lenb@kernel.org, robh@kernel.org, kw@linux.com, f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20210809203323.GA2184624@bjorn-Precision-5520> From: Jeremy Linton Message-ID: Date: Mon, 9 Aug 2021 16:21:21 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210809203323.GA2184624@bjorn-Precision-5520> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210809_142131_119417_87FB56C3 X-CRM114-Status: GOOD ( 21.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, On 8/9/21 3:33 PM, Bjorn Helgaas wrote: > On Mon, Aug 09, 2021 at 02:48:17PM -0500, Jeremy Linton wrote: >> Hi, >> >> On 8/9/21 12:42 PM, Bjorn Helgaas wrote: >>> On Fri, Aug 06, 2021 at 09:55:27PM -0500, Jeremy Linton wrote: >>>> Hi, >>>> >>>> On 8/6/21 5:21 PM, Bjorn Helgaas wrote: >>>>> On Thu, Aug 05, 2021 at 04:11:59PM -0500, Jeremy Linton wrote: >>>>>> The PFTF CM4 is an ACPI platform that is following the PCIe SMCCC >>>>>> standard because its PCIe config space isn't ECAM compliant and is >>>>>> split into two parts. One part for the root port registers and a >>>>>> moveable window which points at a given device's 4K config space. >>>>>> Thus it doesn't have a MCFG (and really any MCFG provided would be >>>>>> nonsense anyway). As Linux doesn't support the PCIe SMCCC standard >>>>>> we key off a Linux specific host bridge _DSD to add custom ECAM >>>>>> ops and cfgres. The cfg op selects between those two regions, as >>>>>> well as disallowing problematic accesses, particularly if the link >>>>>> is down because there isn't an attached device. >>>>> >>>>> I'm not sure SMCCC is *really* relevant here. If it is, an expansion >>>>> of the acronym and a link to a spec would be helpful. >>>>> >>>>> But AFAICT the only important thing here is that it doesn't have >>>>> standard ECAM, and we're going to work around that. >>>> >>>> I will reword it a bit. >>>> >>>>> I don't see anything about _DSD in this series. >>>> >>>> That is the "linux,pci-quirk" in the next patch. >>> >>> The next patch doesn't mention _DSD either. Is it obfuscated by >>> being inside fwnode_property_read_string()? If so, it's well and >>> truly hidden; I gave up trying to connect that with ACPI. >> >> Right, the fwnode stuff works as a DT/ACPI abstraction for reading values >> from firmware tables. In this case the ACPI definition looks something like: >> >> Device(PCI0) { >> ... >> Name (_DSD, Package () { >> ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), >> Package () { >> Package () { "linux-pcie-quirk", "bcm2711" }, >> } >> }) >> >> ... >> } >> >> Which explains a bit of why the underlying code is a bit uh... complicated. > > Wow, that's ... special. > > I think I would include "ecam" or something in the name. There might > be a variety of quirks, e.g., "P2PDMA allowed between root ports", > that could reasonably fit under "linux-pcie-quirk". > I think I mentioned "linux-ecam-quirk-id" in the bit with Rob. How is that? I think the description would be something roughly: MCFG oem id override string which selects a platform specific ECAM accessor quirk. Thanks, _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel