linux-kernel - Re: [PATCH V6 03/13] x86, ia64: Include acpi_pci_{add|remove}_bus to the default pcibios_{add|remove}

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Message-ID: <20160427023429.GE6789@localhost>
Date:	Tue, 26 Apr 2016 21:34:29 -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 03/13] x86, ia64: Include acpi_pci_{add|remove}_bus to
 the default pcibios_{add|remove}_bus implementation.

On Fri, Apr 15, 2016 at 07:06:38PM +0200, Tomasz Nowicki wrote:
> x86 and ia64 are the only arches that implement pcibios_{add|remove}_bus hooks
> and implement them in the same way. Moreover ARM64 is going to do the same.
> So it seems that acpi_pci_{add|remove}_bus is generic enough to be default
> option for pcibios_{add|remove}_bus hooks. Also, it is always safe to run
> acpi_pci_{add|remove}_bus as they have empty stubs for !ACPI case and
> return if ACPI has been switched off in run time.
> 
> After all we can remove x86 and ia64 pcibios_{add|remove}_bus
> implementation.
> 
> Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....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>
> ---
>  arch/ia64/pci/pci.c   | 10 ----------
>  arch/x86/pci/common.c | 10 ----------
>  drivers/pci/probe.c   |  3 +++
>  3 files changed, 3 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
> index 978d6af..be4c9ef 100644
> --- a/arch/ia64/pci/pci.c
> +++ b/arch/ia64/pci/pci.c
> @@ -358,16 +358,6 @@ void pcibios_fixup_bus(struct pci_bus *b)
>  	platform_pci_fixup_bus(b);
>  }
>  
> -void pcibios_add_bus(struct pci_bus *bus)
> -{
> -	acpi_pci_add_bus(bus);
> -}
> -
> -void pcibios_remove_bus(struct pci_bus *bus)
> -{
> -	acpi_pci_remove_bus(bus);
> -}
> -
>  void pcibios_set_master (struct pci_dev *dev)
>  {
>  	/* No special bus mastering setup handling */
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index 381a43c..7763a84 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -170,16 +170,6 @@ void pcibios_fixup_bus(struct pci_bus *b)
>  		pcibios_fixup_device_resources(dev);
>  }
>  
> -void pcibios_add_bus(struct pci_bus *bus)
> -{
> -	acpi_pci_add_bus(bus);
> -}
> -
> -void pcibios_remove_bus(struct pci_bus *bus)
> -{
> -	acpi_pci_remove_bus(bus);
> -}
> -
>  /*
>   * Only use DMI information to set this if nothing was passed
>   * on the kernel command line (which was parsed earlier).
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 8087297..ef569e8 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -12,6 +12,7 @@
>  #include <linux/slab.h>
>  #include <linux/module.h>
>  #include <linux/cpumask.h>
> +#include <linux/pci-acpi.h>
>  #include <linux/pci-aspm.h>
>  #include <linux/aer.h>
>  #include <linux/acpi.h>
> @@ -2101,10 +2102,12 @@ int __weak pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
>  
>  void __weak pcibios_add_bus(struct pci_bus *bus)
>  {
> +	acpi_pci_add_bus(bus);
>  }
>  
>  void __weak pcibios_remove_bus(struct pci_bus *bus)
>  {
> +	acpi_pci_remove_bus(bus);
>  }

Is this buying us something more than just getting rid of these
pcibios functions in the arches?  The arch-specific pcibios methods
by themselves don't seem too onerous, and I don't really want to add
#includes and calls to every firmware interface under the sun.

I admit it's a net removal of 17 lines, but I'm not sure it's a net
reduction in complexity for the reader, who now has to remember that
this ACPI stuff is a no-op on most arches.

As a tangent, some of the stuff in acpi_pci_add_bus() really belongs
elsewhere anyway.  For example, the _DSM stuff should probably be in
acpi_pci_root_create() since it's a one-per-host bridge kind of thing.

>  struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> -- 
> 1.9.1
>