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From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Rob Herring <robh@kernel.org>,
	Scott Branden <scott.branden@broadcom.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, Ley Foon Tan <lftan@altera.com>,
	Russell King <linux@armlinux.org.uk>
Subject: Re: [v4] PCI: improve host drivers compile test coverage
Date: Mon, 18 Jun 2018 13:52:55 +0100	[thread overview]
Message-ID: <20180618125255.GA356@red-moon> (raw)
In-Reply-To: <45f29e28-d3d4-b1e6-249e-ac28b6ec6a36@siemens.com>

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
> >> <scott.branden@broadcom.com> 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 <lorenzo.pieralisi@arm.com>
> >>>>>>>> Cc: Bjorn Helgaas <bhelgaas@google.com>
> >>>>>>>> Cc: linux-pci@vger.kernel.org
> >>>>>>>> Signed-off-by: Rob Herring <robh@kernel.org>
> >>>>>>>
> >>>>>>> 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

  reply	other threads:[~2018-06-18 12:51 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-05 19:31 [PATCH v4] " Rob Herring
2018-05-18 21:42 ` Bjorn Helgaas
2018-05-19 19:22   ` Rob Herring
2018-06-12 17:02 ` [v4] " Guenter Roeck
2018-06-13 10:09   ` Lorenzo Pieralisi
2018-06-13 18:11     ` Guenter Roeck
2018-06-14 16:53       ` Lorenzo Pieralisi
2018-06-15 12:58       ` Lorenzo Pieralisi
2018-06-15 17:55         ` Scott Branden
2018-06-15 17:58           ` Scott Branden
2018-06-18 11:34             ` Lorenzo Pieralisi
2018-06-15 18:34           ` Rob Herring
2018-06-18  9:32             ` Lorenzo Pieralisi
2018-06-18 11:42               ` Jan Kiszka
2018-06-18 12:52                 ` Lorenzo Pieralisi [this message]
2018-06-18 16:53                   ` Jan Kiszka
2018-06-19  9:27                     ` Lorenzo Pieralisi

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