[RFC PATCH 2/2] arm: pcibios: move to generic PCI domains

[Bjorn Helgaas]

On Fri, Oct 31, 2014 at 7:43 AM, Phil Edworthy
<phil.edworthy at renesas.com> wrote:
> Hi Lorenzo,
>
> On 30 October 2014 11:45, Lorenzo wrote:
>> Most if not all ARM PCI host controller device drivers either ignore the
>> domain field in the pci_sys_data structure or just increment it every
>> time a host controller is probed, using it as a domain counter.
>>
>> Therefore, instead of relying on pci_sys_data to stash the domain number
>> in a standard location, ARM pcibios code can be moved to the newly
>> introduced generic PCI domains code, implemented in commits:
>>
>> commit 41e5c0f81d3e676d671d96a0a1fafb27abfbd9
>> ("of/pci: Add pci_get_new_domain_nr() and of_get_pci_domain_nr()")
>>
>> commit 670ba0c8883b576d0aec28bd7a838358a4be1
>> ("PCI: Add generic domain handling")
>>
>> In order to assign a domain number dynamically, the ARM pcibios defines
>> the function, called by core PCI code:
>>
>> void pci_bus_assign_domain_nr(...)
>>
>> that relies on a DT property to define the domain number or falls back to
>> a counter; its usage replaces the current domain assignment code in PCI
>> host controllers present in the kernel.
>>
>> Cc: Arnd Bergmann <arnd at arndb.de>
>> Cc: Phil Edworthy <phil.edworthy at renesas.com>
>> Cc: Jason Gunthorpe <jgunthorpe at obsidianresearch.com>
>> Cc: Jingoo Han <jg1.han at samsung.com>
>> Cc: Bjorn Helgaas <bhelgaas at google.com>
>> Cc: Russell King <linux at arm.linux.org.uk>
>> Cc: Mohit Kumar <mohit.kumar at st.com>
>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
>
> This patch fixes a current problem with R-Car devices where there is an
> internal PCI bridge and an external PCIe bridge on the devices. Both drivers
> work independently but need to be on different domains. Just needed to enable
> PCI_DOMAINS along with this.
> I've done basic testing that the internal PCI and external PCIe work at the
> same time.

Hi Phil,

Thanks for testing this.  Can you give me some more guidance on where
you'd like to see this merged?  Until your comment about this fixing a
current problem on R-Car, I probably would have considered this to be
a cleanup and enhancement and hence material for v3.19.  But if R-Car
is actually broken and this fixes it, maybe this should go in for
v3.18 instead.

If it is currently broken, is there a point where it broke?  I assume
it used to work at one time.  If there's a commit that broke it, it
would be nice to reference that in the changelog and explain exactly
what was broken and how this fixes it.

Bjorn