[PATCH 0/3] Add PCI domain support to R-Car drivers

[Liviu Dudau]

On Tue, Sep 23, 2014 at 11:10:29AM +0100, Phil Edworthy wrote:
> Hi Bjorn,
> 
> On 22 September 2014 22:01, Bjorn wrote:
> > On Mon, Sep 22, 2014 at 10:51:07AM +0100, Phil Edworthy wrote:
> > > The Renesas R-Car devices (r8a7790 and r8a7791) use two PCI controller
> > drivers,
> > > one for an external PCIe slot, the other for an internal PCI bridge to USB
> > > controllers.
> > >
> > > However, they currently do not work at the same time as they use the
> > same PCI
> > > domain and use the same root bus number. We can't use different root
> > bus numbers
> > > due to the way root bus numbers are assigned in pcibios_init_hw() in
> > > arch/arm/kernel/bios32.c.
> > >
> > > Since the two PCI controllers are completely independent, I think it makes
> > sense
> > > to use different PCI domains for them.
> > >
> > > I've marked the third patch as RFC as I am not sure of the impact of
> > enabling
> > > PCI domains for all ARM devices. In the march to 'one kernel to rule them
> > all',
> > > I steered clear of mach specific changes.
> > >
> > > These patches require the following patch from Liviu Dudau:
> > >   [PATCH v11 07/10] OF: Introduce helper function for getting PCI
> > domain_nr
> > > Based on comments on this patch from Jason Gunthorpe, there is still the
> > issue
> > > that the domain numbers may change depending on the ordering at probe
> > time.
> > > However, this can be fixed later on by adding the entries in the DT files.
> > >
> > >
> > > Phil Edworthy (3):
> > >   PCI: rcar-pcie: Add call to get domain nr
> > >   PCI: rcar-internal-pci: Add call to get domain nr
> > >   ARM: Enable PCI domains
> > 
> > I'm deferring these for now because they depend on Liviu's work, which I
> > haven't merged yet, and I suspect some minor adaptation will be required
> > here.
> > 
> > For what it's worth, I agree with Rob's hesitation about mixing lookup with
> > domain number allocation in of_pci_get_domain_nr().  That seems
> > unnecessarily complicated.
> I could create patches to add an optional "pci-domain" property for the R-Car
> PCI drivers, and just attempt to get the property in the drivers. If not found,
> the drivers will assume the domain is 0.
> 
> We would then have fixed PCI domain numbering and I don't have to worry about
> Liviu's work.

I will split the current of_pci_get_domain_nr() even further and replace it with
two functions: pci_get_domain_nr() which will do just the allocation (still based
on the boolean flag passed as parameter) and of_get_pci_domain_nr() that will
retrieve a "linux,pci-domain" value from a property belonging to a given device
node.

I plan to leave for the moment the check for mandatory presence of "linux,pci-domain"
to the host bridge driver so that everyone can implement their own policies.

How does that sound?

Best regards,
Liviu

> 
> Would that be ok?
>  
> Thanks
> Phil
> 

-- 
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