Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus domain number.

Bjorn Helgaas
2016-04-27T02:26:49Z

On Fri, Apr 15, 2016 at 07:06:37PM +0200, Tomasz Nowicki wrote:
> As we now have valid PCI host bridge device reference we can
> introduce code that is going to find its bus domain number using
> ACPI _SEG method.
>
> Note that _SEG method is optional, therefore _SEG absence means
> that all PCI buses belong to domain 0.
>
> While at it, for the sake of code clarity we put ACPI and DT domain
> assign methods into the corresponding helpers.
>
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> Reviewed-by: Liviu Dudau <Liviu.Dudau@arm.com>
> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> Tested-by: Jeremy Linton <jeremy.linton@arm.com>
> Tested-by: Duc Dang <dhdang@apm.com>
> Tested-by: Dongdong Liu <liudongdong3@huawei.com>
> Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
> Tested-by: Graeme Gregory <graeme.gregory@linaro.org>
> Tested-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> drivers/acpi/pci_root.c | 18 ++++++++++++++++++
> drivers/pci/pci.c | 11 +++++++++--
> include/linux/pci-acpi.h | 2 ++
> 3 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 4581e0e..d9a70c4 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -419,6 +419,24 @@ out:
> }
> EXPORT_SYMBOL(acpi_pci_osc_control_set);
>
> +int acpi_pci_bus_domain_nr(struct device *parent)
> +{
> + struct acpi_device *acpi_dev = to_acpi_device(parent);
> + unsigned long long segment = 0;
> + acpi_status status;
> +
> + /*
> + * If _SEG method does not exist, following ACPI spec (6.5.6)
> + * all PCI buses belong to domain 0.
> + */
> + status = acpi_evaluate_integer(acpi_dev->handle, METHOD_NAME__SEG, NULL,
> + &segment);

We already have code in acpi_pci_root_add() to evaluate _SEG. We
don't want to evaluate it *twice*, do we?

I was sort of expecting that if you added it here, we'd remove the
existing call, but it looks like you're keeping both?

> + if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)
> + dev_err(&acpi_dev->dev, "can't evaluate _SEG\n");
> +
> + return segment;
> +}
> +
> static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
> {
> u32 support, control, requested;
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 25e0327..1a74e87 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -19,6 +19,7 @@
> #include <linux/spinlock.h>
> #include <linux/string.h>
> #include <linux/log2.h>
> +#include <linux/pci-acpi.h>
> #include <linux/pci-aspm.h>
> #include <linux/pm_wakeup.h>
> #include <linux/interrupt.h>
> @@ -4779,7 +4780,7 @@ 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)
> {
> static int use_dt_domains = -1;
> int domain = -1;
> @@ -4823,7 +4824,13 @@ 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(parent);
> }
> #endif
> #endif
> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index 89ab057..a72e22d 100644
> --- a/include/linux/pci-acpi.h
> +++ b/include/linux/pci-acpi.h
> @@ -22,6 +22,7 @@ static inline acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev)
> {
> return acpi_remove_pm_notifier(dev);
> }
> +extern int acpi_pci_bus_domain_nr(struct device *parent);
> extern phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle);
>
> static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
> @@ -109,6 +110,7 @@ extern const u8 pci_acpi_dsm_uuid[];
> #else /* CONFIG_ACPI */
> static inline void acpi_pci_add_bus(struct pci_bus *bus) { }
> static inline void acpi_pci_remove_bus(struct pci_bus *bus) { }
> +static inline int acpi_pci_bus_domain_nr(struct device *parent) { return -1; }
> #endif /* CONFIG_ACPI */
>
> #ifdef CONFIG_ACPI_APEI
> --
> 1.9.1
>
> --
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