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From: Scott Branden <scott.branden@broadcom.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Guenter Roeck <linux@roeck-us.net>
Cc: 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: Fri, 15 Jun 2018 10:55:37 -0700	[thread overview]
Message-ID: <980b68c0-6034-b495-753f-c75c04e0f5d1@broadcom.com> (raw)
In-Reply-To: <20180615125847.GA7735@e107981-ln.cambridge.arm.com>

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?
>
> 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.

  reply	other threads:[~2018-06-15 17:55 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 [this message]
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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