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From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Scott Branden <scott.branden@broadcom.com>
Cc: Guenter Roeck <linux@roeck-us.net>, Rob Herring <robh@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, Jan Kiszka <jan.kiszka@siemens.com>,
	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 12:34:41 +0100	[thread overview]
Message-ID: <20180618113440.GA338@red-moon> (raw)
In-Reply-To: <3d84b647-1bc5-3b56-bca3-7a7a72d31c21@broadcom.com>

On Fri, Jun 15, 2018 at 10:58:19AM -0700, Scott Branden wrote:
> 
> 
> On 18-06-15 10:55 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 <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?
> as well as arm64/configs/defconfig?  Rather than having to change
> all the defconfigs perhaps can to make default y in Kconfig for
> architectures that should have it as such?

I can't do that on ARM, this would force PCI_DOMAINS on platforms
that never relied on it and that can trigger regressions.

It is unfortunate but the safest option consists in selecting
PCI_DOMAINS in the respective ARCH_* options I think.

Lorenzo

  reply	other threads:[~2018-06-18 11:33 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 [this message]
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
2018-06-18 16:53                   ` Jan Kiszka
2018-06-19  9:27                     ` Lorenzo Pieralisi

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