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=-4.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 8BCEFC4338F for ; Mon, 9 Aug 2021 20:35:40 +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 32DF660F35 for ; Mon, 9 Aug 2021 20:35:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 32DF660F35 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=1i5lRcVIH11rL+TFqEjaMheeR/pxXFqgs9UF9vyqt+k=; b=4G0tpecHQJc74D 5g+v8CkL+03OAFb8yM7lPz8JPqEgr7BxxuAEeAyGgLOELVSyVrqhZ1GoOr0ktb7vC7oFc+1mFWRvj +uW9DqYXiEOhqQwZDunn9Dm21+kMKvuZVFCN6MoIX4qie97sMGL39K4XJ3wkp5iVVZKFm5/y8Wqhh tC18qQznaAm1wMmhFjgISOHCXrLJPns9NI7ytq7cXbionHNP0zS3YwjioYAF8qRY69QOULvmaov8p ws1GcAnSIHb2Kf+hfQSpJedkuXw1eYcc93Vkolbe2scWryWdNm3vWljN3iQxexYjeAlyPGJhiv0yt FIJCMQARG+yupWsaEYlg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mDBxh-001xXX-P5; Mon, 09 Aug 2021 20:33:29 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mDBxd-001xX0-IH; Mon, 09 Aug 2021 20:33:26 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id B1BDB60F38; Mon, 9 Aug 2021 20:33:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628541205; bh=DFiNEUy2lvl0A6Ke0FlRdCTRadumSQO3fJWSprWIjkY=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=IPtXplkkizVttFmHqlKMMFVrf/9c28Yq43Zod3JrNDwkRD6vsFt7in9VpcExI6znz YoJLbOclV7GGtf3DQoNfEnIGkfppFNgBtwGZ4c5kOP8Ly4aW7LX/fMgTKcd4Zwi5gx DVqlkFbvbNjB2HZ8A9uVNJXUocSQb21qDkD4E+yM9p9y7mPIGwUeYwtcXWwo9itZ5p 2LOYzvN/u/RSkAhNNJ4m2D/Y6shJp3G7P7ewVxVZ1kYaehrZ6rFn+4bGJSHEEWPIZ7 XFLMY3N8Bh3e0CGavp3WrAS4smZFoIu5ySgfUXuhKQ1eNdU4kTeFeAH+VLy80TJJuZ b3tCIaSJlRbeg== Date: Mon, 9 Aug 2021 15:33:23 -0500 From: Bjorn Helgaas To: Jeremy Linton 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 Subject: Re: [PATCH 2/3] PCI: brcmstb: Add ACPI config space quirk Message-ID: <20210809203323.GA2184624@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4d4732b9-e8df-3803-2db7-c6eef1196269@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210809_133325_670086_2B2B0ECC X-CRM114-Status: GOOD ( 30.29 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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". _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel