Re: [v4] PCI: improve host drivers compile test coverage

[Scott Branden <scott.branden@broadcom.com>]

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?
>
>>
>> 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.
>