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From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Rob Herring <robh@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Scott Branden <scott.branden@broadcom.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: Fri, 15 Jun 2018 13:58:47 +0100	[thread overview]
Message-ID: <20180615125847.GA7735@e107981-ln.cambridge.arm.com> (raw)
In-Reply-To: <20180613181146.GA28856@roeck-us.net>

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).

If I hear no complaints I will post it for inclusion, we cannot leave
things as they are.

Lorenzo

-- >8 --
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2a78bdef9a24..1d415aeb54b4 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1244,8 +1244,14 @@ config PCI
 	  VESA. If you have PCI, say Y, otherwise N.
 
 config PCI_DOMAINS
-	bool
+	bool "Support for multiple PCI domains"
 	depends on PCI
+	help
+	  Enable PCI domains kernel management. Say Y if your machine
+	  has a PCI bus hierarchy that requires more than one PCI
+	  domain (aka segment) to be correctly managed. Say N otherwise.
+
+	  If you don't know what to do here, say N.
 
 config PCI_DOMAINS_GENERIC
 	def_bool PCI_DOMAINS
diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 18fa09b3ac8f..cc9fa02d32a0 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -96,7 +96,6 @@ config PCI_HOST_GENERIC
 	depends on OF
 	select PCI_HOST_COMMON
 	select IRQ_DOMAIN
-	select PCI_DOMAINS
 	help
 	  Say Y here if you want to support a simple generic PCI host
 	  controller, such as the one emulated by kvmtool.
@@ -138,7 +137,6 @@ config PCI_VERSATILE
 
 config PCIE_IPROC
 	tristate
-	select PCI_DOMAINS
 	help
 	  This enables the iProc PCIe core controller support for Broadcom's
 	  iProc family of SoCs. An appropriate bus interface driver needs
@@ -176,7 +174,6 @@ config PCIE_IPROC_MSI
 config PCIE_ALTERA
 	bool "Altera PCIe controller"
 	depends on ARM || NIOS2 || COMPILE_TEST
-	select PCI_DOMAINS
 	help
 	  Say Y here if you want to enable PCIe controller support on Altera
 	  FPGA.
-- 
2.15.0

  parent reply	other threads:[~2018-06-15 12:58 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 [this message]
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
2018-06-18 16:53                   ` Jan Kiszka
2018-06-19  9:27                     ` Lorenzo Pieralisi

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