Messages in this thread Patch in this message | | | Subject | Re: [PATCH V8 5/9] pci, acpi: add acpi hook to assign domain number. | From | Tomasz Nowicki <> | Date | Wed, 8 Jun 2016 12:21:19 +0200 |
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Hi Bjorn,
On 08.06.2016 02:15, Bjorn Helgaas wrote: > Hi Tomasz, > > On Mon, May 30, 2016 at 05:14:18PM +0200, Tomasz Nowicki wrote: >> PCI core code provides a config option (CONFIG_PCI_DOMAINS_GENERIC) >> that allows assigning the PCI bus domain number generically by >> relying on device tree bindings, and falling back to a simple counter >> when the respective DT properties (ie "linux,pci-domain") are not >> specified in the host bridge device tree node. >> >> In a similar way, when a system is booted through ACPI, architectures >> that are selecting CONFIG_PCI_DOMAINS_GENERIC (ie ARM64) require kernel >> hooks to retrieve the domain number so that the PCI bus domain number >> set-up can be handled seamlessly with DT and ACPI in generic core code >> when CONFIG_PCI_DOMAINS_GENERIC is selected. >> >> Since currently it is not possible to retrieve a pointer to the PCI >> host bridge ACPI device backing the host bridge from core PCI code >> (which would allow retrieving the domain number in an arch agnostic >> way through the ACPI _SEG method), an arch specific ACPI hook has to >> be declared and implemented by all arches that rely on >> CONFIG_PCI_DOMAINS_GENERIC to retrieve the domain number and set it >> up in core PCI code. >> >> For the aforementioned reasons, this patch introduces a dummy >> acpi_pci_bus_domain_nr() hook in preparation for per-arch implementation >> of the same to retrieve the domain number on a per-arch basis when >> the system boots through ACPI. >> >> For the sake of code clarity the current code implementing generic >> domain number assignment (ie pci_bus_assign_domain_nr(), selected by >> CONFIG_PCI_DOMAINS_GENERIC) is reshuffled so that the code implementing >> the DT domain assignment function is stubbed out into a corresponding >> helper, so that DT and ACPI functions are clearly separated in >> preparation for arches acpi_pci_bus_domain_nr() implementations. >> >> Signed-off-by: Tomasz Nowicki <tn@semihalf.com> >> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> >> --- >> drivers/pci/pci.c | 11 +++++++++-- >> include/linux/pci.h | 1 + >> 2 files changed, 10 insertions(+), 2 deletions(-) >> >> 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?
pci_bus_assign_domain_nr() goes with pci_domain_nr() as an option for CONFIG_PCI_DOMAINS_GENERIC. pci_domain_nr() is used commonly outside drivers/pci so we would need to split these calls then, thus personally I think it would be better to keep both in inclue/linux/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 can. I do not see much difference between pci_bus_domain_nr() and pci_domain_nr() which we already have so how about calling it pci_bus_find_domain_nr instead? Lorenzo, any strong preference for it?
> > That would be two new patches, if this makes sense. > > And this patch would only rename pci_bus_assign_domain_nr() to > of_pci_bus_domain_nr() and add the pci_bus_domain_nr() wrapper.
Giving that we would keep prototypes in inclue/linux/pci.h
1. First patch would rename pci_bus_assign_domain_nr() to pci_bus_find_domain_nr() and it would return domain number so that we could do: ... pci_create_root_bus(...) { ... b->domain_nr = pci_bus_domain_nr(...); ... }
2. Second patch would transform pci_bus_find_domain_nr() to be the wrapper for of_pci_bus_domain_nr()
3. Third patch would add stub definition, the ARM64 definition and the new call acpi_pci_bus_domain_nr() in pci_bus_find_domain_nr() wrapper.
Does this plan sound reasonable?
> >> { >> static int use_dt_domains = -1; >> int domain = -1; >> @@ -4985,7 +4986,13 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent) >> domain = -1; >> } >> >> - bus->domain_nr = domain; >> + return domain; >> +} >> + >> +void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent) >> +{ >> + bus->domain_nr = acpi_disabled ? of_pci_bus_domain_nr(parent) : >> + acpi_pci_bus_domain_nr(bus); >> } >> #endif >> #endif >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index 12349de..bba4053 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -1390,6 +1390,7 @@ static inline int pci_domain_nr(struct pci_bus *bus) >> { >> return bus->domain_nr; >> } >> +static inline int acpi_pci_bus_domain_nr(struct pci_bus *bus) { return -1; } > > I would split the addition of acpi_pci_bus_domain_nr() to a separate > patch and include the ARM64 definition in that same patch. That patch > would only add this stub definition, the ARM64 definition, and the new > call in pci_bus_domain_nr().
OK
Thanks, Tomasz
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