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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 CBC5BC4320E for ; Mon, 9 Aug 2021 17:42:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B128660238 for ; Mon, 9 Aug 2021 17:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234521AbhHIRnI (ORCPT ); Mon, 9 Aug 2021 13:43:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:42144 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234154AbhHIRnG (ORCPT ); Mon, 9 Aug 2021 13:43:06 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B4C3660F25; Mon, 9 Aug 2021 17:42:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628530966; bh=FSFPv4kDztNyzO9/5NElHuOFEoE9ULfv2/yH+18aDsg=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=VNrWPeDdTAiBVFGd4tE8zpWxdKdmy4uZNfT1xG9Ey8dAH7dGzy2c31IkFE9wqhszF sPg1ZS08jMOcY++hBBMKJl46omOGv26RAgaUHhwtqzouT8be3ihPXpXc2BVOWceOzr VzLE4PwGgZYl82onsupTZbAB6RyTgcbYud/IfXyqJflAMDkDS4adDqd3HYEu+Rv/q7 eQ3acQ0wCZNInKHLW3sdL7fjtvpyFj8hL8jtrfliA/lKHv6Dp11tnIevVKPooqs2zB DHZKTfDCPZXc1Gn8wvspTzXBrEGJKKFGvCBL1CQQPy9mEV2B7pfeKfJjHPa9dQnSsO S/yuhaEMlYO+g== Date: Mon, 9 Aug 2021 12:42:44 -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: <20210809174244.GA2167737@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51a11c89-d49b-7367-a75c-13016a2ea5d9@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Bjorn