On Tue, Jan 20, 2015 at 12:26:57PM +0000, Tomasz Nowicki wrote:
On 20.01.2015 12:00, Catalin Marinas wrote:
On Tue, Jan 20, 2015 at 02:39:16AM +0000, Hanjun Guo wrote:
On 2015年01月19日 18:42, Catalin Marinas wrote:
On Sun, Jan 18, 2015 at 06:25:53AM +0000, Hanjun Guo wrote:
On 2015年01月16日 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
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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?
Not always return -E* or NULL;
For raw_pci_read/write(), they are needed to access the PCI config space before the PCI root bus is created. so they will return 0 if access to PCI config space is ok; pci_acpi_scan_root() will return root bus pointer if it is successfully created.
OK. So what's the plan for implementing these functions properly. For the raw_pci_read/write, the comment states "replace with an architecture-specific setup routine". What does this mean?
raw_pci_read/write will use MMCONFIG code to access PCI config space. Please see my patch set: http://lkml.iu.edu/hypermail/linux/kernel/1411.2/02753.html which is going to refactor the x86 specific code so it would be usable for ARM64 too.
OK. Thanks for the information.