linux-kernel - Re: [PATCH 1/1] PCI: add acpi_find_root_bridge

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Message-ID: <20080818175402.GA23155@ldl.fc.hp.com>
Date:	Mon, 18 Aug 2008 11:54:02 -0600
From:	Alex Chiang <achiang@...com>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	jbarnes@...tuousgeek.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, kristen.c.accardi@...el.com,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Subject: Re: [PATCH 1/1] PCI: add acpi_find_root_bridge_handle

* Jiri Slaby <jirislaby@...il.com>:
> Hi,
> 
> I'm sending an update proposed by Alex. Consider it and drop or merge :).
> --
> 
> Consolidate finding of a root bridge and getting its handle to the
> one inline function. It's cut&pasted on multiple places. Use this
> new inline in those.
> 
> Signed-off-by: Jiri Slaby <jirislaby@...il.com>
> Cc: Jesse Barnes <jbarnes@...tuousgeek.org>
> Cc: Alex Chiang <achiang@...com>
> Cc: kristen.c.accardi@...el.com
> Cc: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
> ---
>  drivers/pci/hotplug/acpi_pcihp.c   |    5 +----
>  drivers/pci/pcie/aer/aerdrv_acpi.c |    7 +------
>  include/linux/pci-acpi.h           |   10 ++++++++++
>  3 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
> index bd83197..e17ef54 100644
> --- a/drivers/pci/hotplug/acpi_pcihp.c
> +++ b/drivers/pci/hotplug/acpi_pcihp.c
> @@ -404,10 +404,7 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags)
>  	 * OSHP within the scope of the hotplug controller and its parents,
>  	 * upto the host bridge under which this controller exists.
>  	 */
> -	while (pdev->bus->self)
> -		pdev = pdev->bus->self;
> -	handle = acpi_get_pci_rootbridge_handle(pci_domain_nr(pdev->bus),
> -			pdev->bus->number);
> +	handle = acpi_find_root_bridge_handle(pdev);
>  	if (handle) {
>  		acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
>  		dbg("Trying to get hotplug control for %s\n",
> diff --git a/drivers/pci/pcie/aer/aerdrv_acpi.c b/drivers/pci/pcie/aer/aerdrv_acpi.c
> index 30f581b..6dd7b13 100644
> --- a/drivers/pci/pcie/aer/aerdrv_acpi.c
> +++ b/drivers/pci/pcie/aer/aerdrv_acpi.c
> @@ -36,12 +36,7 @@ int aer_osc_setup(struct pcie_device *pciedev)
>  	if (acpi_pci_disabled)
>  		return -1;
>  

The reason I even knew about aer_osc_setup() was because I found
the while (pdev->bus->self) idiom a bit confusing, so I did a git
grep to see if it was used anywhere else in the kernel. Luckily,
the below comment was there, and I found it helpful.

> -	/* Find root host bridge */

So can we move this coment ^^ into your new inline below?

Thanks!

/ac

> -	while (pdev->bus->self)
> -		pdev = pdev->bus->self;
> -	handle = acpi_get_pci_rootbridge_handle(
> -		pci_domain_nr(pdev->bus), pdev->bus->number);
> -
> +	handle = acpi_find_root_bridge_handle(pdev);
>  	if (handle) {
>  		pcie_osc_support_set(OSC_EXT_PCI_CONFIG_SUPPORT);
>  		status = pci_osc_control_set(handle,
> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index 3ba2506..807847a 100644
> --- a/include/linux/pci-acpi.h
> +++ b/include/linux/pci-acpi.h
> @@ -57,6 +57,14 @@ static inline acpi_status pcie_osc_support_set(u32 flags)
>  {
>  	return __pci_osc_support_set(flags, PCI_EXPRESS_ROOT_HID_STRING);
>  }
> +static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
> +{
> +	while (pdev->bus->self)
> +		pdev = pdev->bus->self;
> +
> +	return acpi_get_pci_rootbridge_handle(pci_domain_nr(pdev->bus),
> +			pdev->bus->number);
> +}
>  #else
>  #if !defined(AE_ERROR)
>  typedef u32 		acpi_status;
> @@ -66,6 +74,8 @@ static inline acpi_status pci_osc_control_set(acpi_handle handle, u32 flags)
>  {return AE_ERROR;}
>  static inline acpi_status pci_osc_support_set(u32 flags) {return AE_ERROR;} 
>  static inline acpi_status pcie_osc_support_set(u32 flags) {return AE_ERROR;}
> +static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
> +{ return NULL; }
>  #endif
>  
>  #endif	/* _PCI_ACPI_H_ */
> -- 
> 1.6.0
> 
> --
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