From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.101.70]:33600 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933352AbeFRMvZ (ORCPT ); Mon, 18 Jun 2018 08:51:25 -0400 Date: Mon, 18 Jun 2018 13:52:55 +0100 From: Lorenzo Pieralisi To: Jan Kiszka Cc: Rob Herring , Scott Branden , Guenter Roeck , Bjorn Helgaas , linux-pci@vger.kernel.org, Ley Foon Tan , Russell King Subject: Re: [v4] PCI: improve host drivers compile test coverage Message-ID: <20180618125255.GA356@red-moon> References: <20180405193154.27897-1-robh@kernel.org> <20180612170229.GA10141@roeck-us.net> <20180613100935.GA7707@e107981-ln.cambridge.arm.com> <20180613181146.GA28856@roeck-us.net> <20180615125847.GA7735@e107981-ln.cambridge.arm.com> <980b68c0-6034-b495-753f-c75c04e0f5d1@broadcom.com> <20180618093201.GA18994@e107981-ln.cambridge.arm.com> <45f29e28-d3d4-b1e6-249e-ac28b6ec6a36@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <45f29e28-d3d4-b1e6-249e-ac28b6ec6a36@siemens.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Mon, Jun 18, 2018 at 01:42:25PM +0200, Jan Kiszka wrote: > On 2018-06-18 11:32, Lorenzo Pieralisi wrote: > > On Fri, Jun 15, 2018 at 12:34:51PM -0600, Rob Herring wrote: > >> On Fri, Jun 15, 2018 at 11:55 AM, Scott Branden > >> wrote: > >>> Hi Lorenzo, > >>> > >>> > >>> > >>> On 18-06-15 05:58 AM, Lorenzo Pieralisi wrote: > >>>> > >>>> On Wed, Jun 13, 2018 at 11:11:46AM -0700, Guenter Roeck wrote: > >>>>> > >>>>> On Wed, Jun 13, 2018 at 11:09:35AM +0100, Lorenzo Pieralisi wrote: > >>>>>> > >>>>>> [+Jan, Ley Foon, RMK] > >>>>>> > >>>>>> On Tue, Jun 12, 2018 at 10:02:29AM -0700, Guenter Roeck wrote: > >>>>>>> > >>>>>>> On Thu, Apr 05, 2018 at 02:31:54PM -0500, Rob Herring wrote: > >>>>>>>> > >>>>>>>> Add COMPILE_TEST on driver config options with it. Some ARM drivers > >>>>>>>> still have arch dependencies, so we have to keep those dependent on > >>>>>>>> ARM. > >>>>>>>> > >>>>>>>> Cc: Lorenzo Pieralisi > >>>>>>>> Cc: Bjorn Helgaas > >>>>>>>> Cc: linux-pci@vger.kernel.org > >>>>>>>> Signed-off-by: Rob Herring > >>>>>>> > >>>>>>> This patch has the undesirable side effect that it selects PCI_DOMAINS > >>>>>>> for > >>>>>>> sparc32:allmodconfig, which in turn results in > >>>>>>> > >>>>>>> drivers/ata/pata_ali.c: In function 'ali_init_chipset': > >>>>>>> drivers/ata/pata_ali.c:469:38: error: > >>>>>>> implicit declaration of function 'pci_domain_nr'; did you mean > >>>>>>> 'pci_iomap_wc'? > >>>>>>> > >>>>>>> Unfortunately, 37bd62d224c82 ("PCI: Enable PCI_DOMAINS along with > >>>>>>> generic > >>>>>>> PCI host controller") has pretty much the same result. No idea how to > >>>>>>> fix > >>>>>>> the problem, so I won't even try. > >>>>>> > >>>>>> Sorry about that. > >>>>>> > >>>>>> One option would consist in removing all PCI_DOMAINS selection from > >>>>>> drivers/pci/controller/Kconfig and delegate it to arches even though > >>>>>> this would force PCI_DOMAINS selection on all ARM platforms (it is > >>>>>> already selected for ARCH_MULTIPLATFORM). > >>>>>> > >>>>>> Or we add back arch dependency to the relevant host bridges. > >>>>>> > >>>>>> Everything else I have in mind seems overkill to me given that this > >>>>>> patch was added to improve test coverage (we could add a default > >>>>>> pci_domain_nr() stub - weak or #define - that returns 0 in case arches > >>>>>> do not provide an implementation but do we really want to do that ?). > >>>>>> > >>>>>> Thoughts appreciated. > >>>>>> > >>>>> From the definition of PCI_DOMAINS, I suspect the original idea was that > >>>>> drivers should depend on it, not select it. Especially auto-selecting > >>>>> it with PCI_HOST_GENERIC seems like a bad idea to me. However, that is > >>>>> just me. I'll leave it up to Bjorn to decide what if anything he wants > >>>>> to do about it. > >>>> > >>>> Here is a patch that should reinstate the previous behaviour but > >>>> it will make PCI_DOMAINS a visible option on ARM 32-bit systems; whether > >>>> that's acceptable that's the question I need to answer, it should > >>>> honour old configs and it does not force PCI_DOMAINS selection on > >>>> non-DT arch/arm PCI host controllers (that do not need PCI_DOMAINS > >>>> anyway so I suspect that enabling it on all ARM 32-bit platforms > >>>> should not break anything but I preferred to be cautious). > >>> > >>> I think this change will also require a patch enabling CONFIG_PCI_DOMAINS in > >>> multi_v7_defconfig and iproc_defconfig at the very least? > >> > >> Perhaps the sub-arches that want this should select it. It is more a > >> platform option/decision more than a controller option. > > > > Yes, that makes sense, I assume ARCH_VIRT is a sensible choice for > > virtual machines configuration, Jan ? > > > > I will add a PCI_DOMAINS selection to all (ARM) arches that select > > PCI_DOMAINS in drivers/pci/controller/Kconfig. > > > > For Jailhouse configurations I need Jan's input, I assume adding > > the selection to ARCH_VIRT is the correct way forward, please let > > me know asap. > > So far, there is no need on ARM or ARM64 declare a special platform in > order to run as Jailhouse (secondary) guest. > > My original patch was just about making PCI_DOMAINS manually > configurable, which would have been fine for our use case. I need more details on your system configuration to make sure we can fix this in a way that does not upset anybody; I am not a big fan of making PCI_DOMAINS visible since it affects other platforms and it is different from how it is managed for all other arches, so please provide details. Thanks, Lorenzo