From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.101.70]:54060 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750723AbbLDMmg (ORCPT ); Fri, 4 Dec 2015 07:42:36 -0500 Date: Fri, 4 Dec 2015 12:43:45 +0000 From: Lorenzo Pieralisi To: "Jayachandran C." Cc: linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tomasz Nowicki Subject: Re: [RFC PATCH 0/3] ACPI PCI support for arm64 Message-ID: <20151204124345.GA4169@red-moon> References: <1449095086-5138-1-git-send-email-jchandra@broadcom.com> <20151203105628.GD2110@red-moon> <20151203184128.GA5890@jayachandranc.netlogicmicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20151203184128.GA5890@jayachandranc.netlogicmicro.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Fri, Dec 04, 2015 at 12:11:30AM +0530, Jayachandran C. wrote: > On Thu, Dec 03, 2015 at 10:56:28AM +0000, Lorenzo Pieralisi wrote: > > [CC'ing Tomasz] > > > > On Thu, Dec 03, 2015 at 03:54:43AM +0530, Jayachandran C wrote: > > > This is a very simple and generic implementation of a PCI host controller > > > based on ACPI. This approach does not pull in the MMCONFIG and ECAM code > > > from x86. > > > > Why ? Tomasz's patchset does not move MMCONFIG and ECAM code to the generic > > PCI layer for fun, > > Honestly, Lorenzo, I can see that it was not fun :) Ok, maybe you have not noticed it was done on Bjorn's request to consolidate ECAM (ie pulling that code out of x86) instead of reinventing the wheel for arm64. > > it is generic code and should be shared by all > > architectures and most importantly we should not add more churn on > > top of it which would complicate consolidation even further. > > There is no need for such a common/generic infrastructure to > walk thru a simple table. In my opinion, trying to do this added > a lot of complexity into what should be a very simple patchset. > > The x86 code has to deal with a lot more fw/hw issues and I fail > to see why that mess should be brought into the a new architecture. See above. We can't keep adding code that does the same thing as code already in the mainline. > > > It is important for us to have a working ACPI based PCI host controller > > > implementation for arm64, so I thought I would post this as a simple > > > and less disruptive alternative. > > > > It is important for everyone but that's not a reason granting shortcuts. > > I am suggesting a simpler (and maybe better) implementation, which > is much easier to review and merge - not a shortcut. You are suggesting adding code to parse the MCFG table, it exists today and should be consolidated instead of adding on top of it. > > > This is tested with arm64 QEMU and OVMF. Comments are very welcome. > > > > Tomasz's patch went through several review cycles, please help review > > it and test it, that's my comment. > > > > A new version should be posted soon, previous version here: > > > > https://lkml.org/lkml/2015/10/27/504 > > It seems to be v1, I did not see any ACKs from maintainers either - > sorry if I am missing something here. That patchset went through several reviews already, they just reset the version. I agree with you it is time we got this done, with Tomasz's code, your code or any combination thereof, please help us get this through, thanks. Lorenzo