From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f194.google.com ([209.85.216.194]:34799 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730634AbeHISa3 (ORCPT ); Thu, 9 Aug 2018 14:30:29 -0400 Received: by mail-qt0-f194.google.com with SMTP id m13-v6so7099051qth.1 for ; Thu, 09 Aug 2018 09:04:56 -0700 (PDT) Subject: Re: [RFC] ARM64, PCIe, annd ACPI To: Lorenzo Pieralisi Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, Tomasz Nowicki , Vladimir Olovyannikov , BCM Kernel Feedback References: <89484aa0-08c4-0cff-500d-407d21e2f5fd@broadcom.com> <20180808093822.GA25150@e107981-ln.cambridge.arm.com> <20180809085923.GA13428@e107981-ln.cambridge.arm.com> <9b5b5918-1492-df65-5b63-678b4a35ecb9@broadcom.com> <20180809154151.GB20329@red-moon> <27e3dd65-50d9-08a2-9639-b7d229f48227@broadcom.com> <20180809160035.GC20329@red-moon> From: Ray Jui Message-ID: Date: Thu, 9 Aug 2018 09:04:52 -0700 MIME-Version: 1.0 In-Reply-To: <20180809160035.GC20329@red-moon> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: Hi Lorenzo, On 8/9/2018 9:00 AM, Lorenzo Pieralisi wrote: > On Thu, Aug 09, 2018 at 08:44:34AM -0700, Ray Jui wrote: >> Hi Lorenzo, >> >> On 8/9/2018 8:41 AM, Lorenzo Pieralisi wrote: >>> On Thu, Aug 09, 2018 at 07:57:52AM -0700, Ray Jui wrote: >>> >>> [...] >>> >>>>> As I said ARM64 ACPI PCI kernel support is in the mainline today and I >>>>> am not willing to merge any more MCFG quirks at driver level - the >>>>> information is out there, it is public and must be followed, either >>>>> designers do that or no ACPI PCI support on your platform, sorry. >>>>> >>>>> Lorenzo >>>>> >>>> >>>> I just want to make sure I interpret this properly. This means if >>>> the PCIe controller hardware does not support ECAM, there's pretty >>>> much no way around it with SW based workaround going forward with >>>> mainline kernel? >>> >>> Yes. >>> >>>> What about for the PCIe controller that was designed a few years back? >>> >>> It will bootstrap with DT :) >> >> Okay, one more quick question, what about for distributions that >> will eventually disable DT and force ACPI? > > ACPI PCI support revolves around a FW model that requires, among other > things, ECAM and its firmware description, MCFG table, to work. > > If the host controller is not ECAM compliant it is not PCI firmware > compliant, so it is not ACPI compliant, you can't run ACPI only > distributions on it. > > It is a model that has been run for decades in basically all > ACPI based systems out there and there is not a reason to > deviate from it, I understand the frustration but that's the > way it is, sorry. > > Thanks, > Lorenzo > Okay that draws the line. Thanks for confirming. Ray