linux-kernel - Re: [PATCH V8 5/9] pci, acpi: add acpi hook to assign domain number.

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Date:	Fri, 10 Jun 2016 18:49:32 +0200
From:	Tomasz Nowicki <tn@...ihalf.com>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Bjorn Helgaas <helgaas@...nel.org>
Cc:	arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
	rafael@...nel.org, hanjun.guo@...aro.org, okaya@...eaurora.org,
	jchandra@...adcom.com, robert.richter@...iumnetworks.com,
	mw@...ihalf.com, Liviu.Dudau@....com, ddaney@...iumnetworks.com,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jcm@...hat.com, andrea.gallo@...aro.org, dhdang@....com,
	jeremy.linton@....com, liudongdong3@...wei.com, cov@...eaurora.org
Subject: Re: [PATCH V8 5/9] pci, acpi: add acpi hook to assign domain number.

On 10.06.2016 17:49, Lorenzo Pieralisi wrote:
> On Fri, Jun 10, 2016 at 04:14:58PM +0100, Lorenzo Pieralisi wrote:
>> Hi Bjorn, Tomasz,
>>
>> On Tue, Jun 07, 2016 at 07:15:59PM -0500, Bjorn Helgaas wrote:
>>
>> [...]
>>
>>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>>>> index eb431b5..2b52178 100644
>>>> --- a/drivers/pci/pci.c
>>>> +++ b/drivers/pci/pci.c
>>>> @@ -7,6 +7,7 @@
>>>>    *	Copyright 1997 -- 2000 Martin Mares <mj@....cz>
>>>>    */
>>>>
>>>> +#include <linux/acpi.h>
>>>>   #include <linux/kernel.h>
>>>>   #include <linux/delay.h>
>>>>   #include <linux/init.h>
>>>> @@ -4941,7 +4942,7 @@ int pci_get_new_domain_nr(void)
>>>>   }
>>>>
>>>>   #ifdef CONFIG_PCI_DOMAINS_GENERIC
>>>> -void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
>>>> +static int of_pci_bus_domain_nr(struct device *parent)
>>>
>>> Can we do a little cleanup before this patch?
>>>
>>>    - pci_bus_assign_domain_nr() is only used inside drivers/pci, so
>>>      maybe we move the prototype to drivers/pci/pci.h?
>>>
>>>    - I don't really like the style of calling a function that
>>>      internally assigns bus->domain_nr.  Could we do something like
>>>      this instead?
>>>
>>>      int pci_bus_domain_nr(...)
>>>      {
>>>        ...
>>>        return domain;
>>>      }
>>>
>>>      ... pci_create_root_bus(...)
>>>      {
>>>        ...
>>>        b->domain_nr = pci_bus_domain_nr(...);
>>
>> We noticed while preparing v9, that this would force us to
>> write an empty pci_bus_domain_nr() prototype for
>> !PCI_DOMAINS_GENERIC (ie every arch but ARM/ARM64) that should
>> return 0 to keep current behaviour unchanged.
>>
>> That's why pci_bus_assign_domain_nr() was there, so that it
>> was compiled out on !PCI_DOMAINS_GENERIC.
>>
>> I really would like v9 to be final so let's fix it before posting it
>> shortly please.
>>
>> For the above we have three options:
>>
>> 1) Leave code as-is in v8
>>
>> 2) in pci_create_root_bus():
>> #ifdef CONFIG_PCI_DOMAINS_GENERIC
>>         b->domain_nr = pci_bus_domain_nr(...);
>> #endif
>>
>> + other changes requested above
>>
>> 3) in pci_create_root_bus()
>>
>> b->domain_nr = pci_bus_domain_nr(...);
>>
>> unguarded and a stub:
>>
>> #ifndef CONFIG_PCI_DOMAINS_GENERIC
>> static inline int pci_bus_domain_nr() { return 0; }
>> #endif
>>
>> + other changes requested above
>
> Actually, Tomasz made me notice that pci_bus.domain_nr is
> only declared for CONFIG_PCI_DOMAINS_GENERIC so (3) is not
> even an option and IMO (2) is not much nicer than code in
> v8 as-is with an ifdef in the middle of pci_create_root_bus().
>

To me (1) is nicer too. Bjorn what is your take on this? This is last 
bit before sending v9.

Thanks,
Tomasz