Re: [PATCH v7 06/17] ARM64 / ACPI: Make PCI optional for ACPI on ARM64

[Catalin Marinas]

On Sun, Jan 18, 2015 at 06:25:53AM +0000, Hanjun Guo wrote:
> On 2015å01æ16æ 17:49, Catalin Marinas wrote:
> > On Wed, Jan 14, 2015 at 03:04:54PM +0000, Hanjun Guo wrote:
> >> --- a/arch/arm64/kernel/pci.c
> >> +++ b/arch/arm64/kernel/pci.c
> >> @@ -10,6 +10,7 @@
> >>    *
> >>    */
> >>
> >> +#include <linux/acpi.h>
> >>   #include <linux/init.h>
> >>   #include <linux/io.h>
> >>   #include <linux/kernel.h>
> >> @@ -68,3 +69,30 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
> >>   	bus->domain_nr = domain;
> >>   }
> >>   #endif
> >> +
> >> +/*
> >> + * raw_pci_read/write - Platform-specific PCI config space access.
> >> + *
> >> + * Default empty implementation.  Replace with an architecture-specific setup
> >> + * routine, if necessary.
> >> + */
> >> +int raw_pci_read(unsigned int domain, unsigned int bus,
> >> +		  unsigned int devfn, int reg, int len, u32 *val)
> >> +{
> >> +	return -EINVAL;
> >> +}
> >> +
> >> +int raw_pci_write(unsigned int domain, unsigned int bus,
> >> +		unsigned int devfn, int reg, int len, u32 val)
> >> +{
> >> +	return -EINVAL;
> >> +}
> >> +
> >> +#ifdef CONFIG_ACPI
> >> +/* Root bridge scanning */
> >> +struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
> >> +{
> >> +	/* TODO: Should be revisited when implementing PCI on ACPI */
> >> +	return NULL;
> >> +}
> >> +#endif
[...]
> > When PCI is enabled and the above functions are compiled in, do they
> > need to return any useful data or just -EINVAL. Are they ever called?
> 
> They will be called if PCI root bridge is defined in DSDT, should I
> print some warning message before it is implemented?

My point: do they need to return real data when a PCI root bridge is
defined in DSDT or you always expect them to always return some -E*? Can
you explain why?

-- 
Catalin
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