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

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Message-ID: <20160427022649.GD6789@localhost>
Date:	Tue, 26 Apr 2016 21:26:49 -0500
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Tomasz Nowicki <tn@...ihalf.com>
Cc:	arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
	rafael@...nel.org, hanjun.guo@...aro.org,
	Lorenzo.Pieralisi@....com, okaya@...eaurora.org,
	jiang.liu@...ux.intel.com, jchandra@...adcom.com,
	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jcm@...hat.com
Subject: Re: [PATCH V6 02/13] pci, acpi: Provide generic way to assign bus
 domain number.

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@...ihalf.com>
> Reviewed-by: Liviu Dudau <Liviu.Dudau@....com>
> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> Tested-by: Jeremy Linton <jeremy.linton@....com>
> Tested-by: Duc Dang <dhdang@....com>
> Tested-by: Dongdong Liu <liudongdong3@...wei.com>
> Tested-by: Hanjun Guo <hanjun.guo@...aro.org>
> Tested-by: Graeme Gregory <graeme.gregory@...aro.org>
> Tested-by: Sinan Kaya <okaya@...eaurora.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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