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

Lorenzo Pieralisi
2016-06-10T15:48:51Z

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@ucw.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().

Thanks,
Lorenzo