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    SubjectRe: [PATCH v7 06/17] ARM64 / ACPI: Make PCI optional for ACPI on ARM64
    On Wed, Jan 14, 2015 at 03:04:54PM +0000, Hanjun Guo wrote:
    > Since PCI is not required in ACPI spec and ARM can run without
    > it, introduce some stub functions to make PCI optional for ACPI,
    > and make ACPI core run without CONFIG_PCI on ARM64.
    >
    > When PCI is enabled on ARM64, ACPI core will need some PCI functions
    > to make it functional, so introduce some empty functions here and
    > implement it later.
    >
    > Since ACPI on X86 and IA64 depends on PCI and this patch only makes
    > PCI optional for ARM64, it will not break anything on X86 and IA64.
    >
    > Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
    > Tested-by: Yijing Wang <wangyijing@huawei.com>
    > Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>

    Is this patch still required, now that we have PCI for arm64? I know the
    ACPI spec doesn't require PCI but do we expect any arm64 servers aimed
    at ACPI without PCIe?

    Anyway, that's not the main point, see more below.

    > diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
    > index 872ba93..fded096 100644
    > --- a/arch/arm64/include/asm/pci.h
    > +++ b/arch/arm64/include/asm/pci.h
    > @@ -24,6 +24,12 @@
    > */
    > #define PCI_DMA_BUS_IS_PHYS (0)
    >
    > +static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
    > +{
    > + /* no legacy IRQ on arm64 */
    > + return -ENODEV;
    > +}
    > +
    > extern int isa_dma_bridge_buggy;
    >
    > #ifdef CONFIG_PCI
    > diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
    > index ce5836c..42fb195 100644
    > --- 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

    Do these functions have anything to do with the subject? You add them in
    arch/arm64/kernel/pci.c which is compiled only when CONFIG_PCI while the
    commit log implies that you add them to allow CONFIG_PCI to be off.

    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?

    > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
    > index 39f3ec1..c346011 100644
    > --- a/drivers/acpi/Makefile
    > +++ b/drivers/acpi/Makefile
    > @@ -43,7 +43,7 @@ acpi-y += processor_core.o
    > acpi-$(CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC) += processor_pdc.o
    > acpi-y += ec.o
    > acpi-$(CONFIG_ACPI_DOCK) += dock.o
    > -acpi-y += pci_root.o pci_link.o pci_irq.o
    > +acpi-$(CONFIG_PCI) += pci_root.o pci_link.o pci_irq.o
    > acpi-y += acpi_lpss.o
    > acpi-y += acpi_platform.o
    > acpi-y += acpi_pnp.o
    > diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
    > index 163e82f..c5ff8ba 100644
    > --- a/drivers/acpi/internal.h
    > +++ b/drivers/acpi/internal.h
    > @@ -26,8 +26,13 @@
    > acpi_status acpi_os_initialize1(void);
    > int init_acpi_device_notify(void);
    > int acpi_scan_init(void);
    > +#ifdef CONFIG_PCI
    > void acpi_pci_root_init(void);
    > void acpi_pci_link_init(void);
    > +#else
    > +static inline void acpi_pci_root_init(void) {}
    > +static inline void acpi_pci_link_init(void) {}
    > +#endif
    > void acpi_processor_init(void);
    > void acpi_platform_init(void);
    > void acpi_pnp_init(void);

    That's a good clean-up.

    > diff --git a/include/linux/pci.h b/include/linux/pci.h
    > index 360a966..1476a66 100644
    > --- a/include/linux/pci.h
    > +++ b/include/linux/pci.h
    > @@ -564,15 +564,6 @@ struct pci_ops {
    > int (*write)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val);
    > };
    >
    > -/*
    > - * ACPI needs to be able to access PCI config space before we've done a
    > - * PCI bus scan and created pci_bus structures.
    > - */
    > -int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
    > - int reg, int len, u32 *val);
    > -int raw_pci_write(unsigned int domain, unsigned int bus, unsigned int devfn,
    > - int reg, int len, u32 val);
    > -
    > struct pci_bus_region {
    > dma_addr_t start;
    > dma_addr_t end;
    > @@ -1329,6 +1320,16 @@ typedef int (*arch_set_vga_state_t)(struct pci_dev *pdev, bool decode,
    > unsigned int command_bits, u32 flags);
    > void pci_register_set_vga_state(arch_set_vga_state_t func);
    >
    > +/*
    > + * ACPI needs to be able to access PCI config space before we've done a
    > + * PCI bus scan and created pci_bus structures.
    > + */
    > +int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
    > + int reg, int len, u32 *val);
    > +int raw_pci_write(unsigned int domain, unsigned int bus, unsigned int devfn,
    > + int reg, int len, u32 val);
    > +void pcibios_penalize_isa_irq(int irq, int active);
    > +
    > #else /* CONFIG_PCI is not enabled */
    >
    > /*
    > @@ -1430,6 +1431,23 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
    > unsigned int devfn)
    > { return NULL; }
    >
    > +static inline struct pci_bus *pci_find_bus(int domain, int busnr)
    > +{ return NULL; }
    > +
    > +static inline int pci_bus_write_config_byte(struct pci_bus *bus,
    > + unsigned int devfn, int where, u8 val)
    > +{ return -ENOSYS; }
    > +
    > +static inline int raw_pci_read(unsigned int domain, unsigned int bus,
    > + unsigned int devfn, int reg, int len, u32 *val)
    > +{ return -ENOSYS; }
    > +
    > +static inline int raw_pci_write(unsigned int domain, unsigned int bus,
    > + unsigned int devfn, int reg, int len, u32 val)
    > +{ return -ENOSYS; }

    So you implement the !CONFIG_PCI functions here to return -ENOSYS while
    the arm64 CONFIG_PCI ones would return -EINVAL. I'm confused.

    --
    Catalin


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