Re: [PATCH V6 01/13] pci, acpi, x86, ia64: Move ACPI host bridge device companion assignment to core code.

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Friday, April 15, 2016 07:06:36 PM Tomasz Nowicki wrote:
> Currently we have two platforms (x86 & ia64) capable of PCI ACPI host
> bridge initialization. They both use arch-specific sysdata to pass down
> parent device reference and both rely on NULL parent in pci_create_root_bus()
> to validate sysdata content.

No, this is not relied on for that.  It is just NULL, because we don't
have a physical parent device representation for the PCI host bridge.

> It looks hacky and prevents us from getting some firmware specific
> info for PCI host controller based on its acpi_device structure
> in generic pci_create_root_bus() function.

You can't get that info without adding ACPI-specific code to that function
anyway.

> However, we overcome that blocker by passing down parent device via
> pci_create_root_bus parameter (as the ACPI device type).

Which is completely wrong.

> Then we use ACPI_COMPANION_SET in core code
> for ACPI boot method only. ACPI_COMPANION_SET is safe to run for all
> cases DT, ACPI and DT&ACPI.
> 
> Since now PCI core code is setting ACPI companion device for us,
> x86 & ia64 specific ACPI companion device setting turns out to be dead now.
> We can get rid of it, including related companion reference from
> PCI sysdata structure. Aslo, PCI_CONTROLLER macro cannot return valid
> companion device anymore. Therefore we need to convert its usage to
> ACPI_COMPANION.
> 
> Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@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>
> ---
>  arch/ia64/hp/common/sba_iommu.c    |  2 +-
>  arch/ia64/include/asm/pci.h        |  1 -
>  arch/ia64/pci/pci.c                | 16 ----------------
>  arch/ia64/sn/kernel/io_acpi_init.c |  4 ++--
>  arch/x86/include/asm/pci.h         |  3 ---
>  arch/x86/pci/acpi.c                | 17 -----------------
>  drivers/acpi/pci_root.c            |  7 ++++++-
>  drivers/pci/probe.c                |  2 ++
>  8 files changed, 11 insertions(+), 41 deletions(-)
> 
> diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
> index a6d6190..78e4444 100644
> --- a/arch/ia64/hp/common/sba_iommu.c
> +++ b/arch/ia64/hp/common/sba_iommu.c
> @@ -1981,7 +1981,7 @@ sba_connect_bus(struct pci_bus *bus)
>  	if (PCI_CONTROLLER(bus)->iommu)
>  		return;
>  
> -	handle = acpi_device_handle(PCI_CONTROLLER(bus)->companion);
> +	handle = acpi_device_handle(ACPI_COMPANION(bus->bridge));
>  	if (!handle)
>  		return;
>  
> diff --git a/arch/ia64/include/asm/pci.h b/arch/ia64/include/asm/pci.h
> index c0835b0..12423f4 100644
> --- a/arch/ia64/include/asm/pci.h
> +++ b/arch/ia64/include/asm/pci.h
> @@ -63,7 +63,6 @@ extern int pci_mmap_legacy_page_range(struct pci_bus *bus,
>  #define pci_legacy_write platform_pci_legacy_write
>  
>  struct pci_controller {
> -	struct acpi_device *companion;
>  	void *iommu;
>  	int segment;
>  	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
> diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
> index 8f6ac2f..978d6af 100644
> --- a/arch/ia64/pci/pci.c
> +++ b/arch/ia64/pci/pci.c
> @@ -301,28 +301,12 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  	}
>  
>  	info->controller.segment = root->segment;
> -	info->controller.companion = device;
>  	info->controller.node = acpi_get_node(device->handle);
>  	INIT_LIST_HEAD(&info->io_resources);
>  	return acpi_pci_root_create(root, &pci_acpi_root_ops,
>  				    &info->common, &info->controller);
>  }
>  
> -int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
> -{
> -	/*
> -	 * We pass NULL as parent to pci_create_root_bus(), so if it is not NULL
> -	 * here, pci_create_root_bus() has been called by someone else and
> -	 * sysdata is likely to be different from what we expect.  Let it go in
> -	 * that case.
> -	 */
> -	if (!bridge->dev.parent) {
> -		struct pci_controller *controller = bridge->bus->sysdata;
> -		ACPI_COMPANION_SET(&bridge->dev, controller->companion);
> -	}
> -	return 0;
> -}
> -
>  void pcibios_fixup_device_resources(struct pci_dev *dev)
>  {
>  	int idx;
> diff --git a/arch/ia64/sn/kernel/io_acpi_init.c b/arch/ia64/sn/kernel/io_acpi_init.c
> index 231234c..e454492 100644
> --- a/arch/ia64/sn/kernel/io_acpi_init.c
> +++ b/arch/ia64/sn/kernel/io_acpi_init.c
> @@ -132,7 +132,7 @@ sn_get_bussoft_ptr(struct pci_bus *bus)
>  	struct acpi_resource_vendor_typed *vendor;
>  
>  
> -	handle = acpi_device_handle(PCI_CONTROLLER(bus)->companion);
> +	handle = acpi_device_handle(ACPI_COMPANION(bus->bridge));
>  	status = acpi_get_vendor_resource(handle, METHOD_NAME__CRS,
>  					  &sn_uuid, &buffer);
>  	if (ACPI_FAILURE(status)) {
> @@ -360,7 +360,7 @@ sn_acpi_get_pcidev_info(struct pci_dev *dev, struct pcidev_info **pcidev_info,
>  	acpi_status status;
>  	struct acpi_buffer name_buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>  
> -	rootbus_handle = acpi_device_handle(PCI_CONTROLLER(dev)->companion);
> +	rootbus_handle = acpi_device_handle(ACPI_COMPANION(dev->bus->bridge));
>          status = acpi_evaluate_integer(rootbus_handle, METHOD_NAME__SEG, NULL,
>                                         &segment);
>          if (ACPI_SUCCESS(status)) {
> diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
> index 9ab7507..24de07d 100644
> --- a/arch/x86/include/asm/pci.h
> +++ b/arch/x86/include/asm/pci.h
> @@ -14,9 +14,6 @@
>  struct pci_sysdata {
>  	int		domain;		/* PCI domain */
>  	int		node;		/* NUMA node */
> -#ifdef CONFIG_ACPI
> -	struct acpi_device *companion;	/* ACPI companion device */
> -#endif
>  #ifdef CONFIG_X86_64
>  	void		*iommu;		/* IOMMU private data */
>  #endif
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index 3cd6983..f4ca17a 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -340,7 +340,6 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  		struct pci_sysdata sd = {
>  			.domain = domain,
>  			.node = node,
> -			.companion = root->device
>  		};
>  
>  		memcpy(bus->sysdata, &sd, sizeof(sd));
> @@ -355,7 +354,6 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  		else {
>  			info->sd.domain = domain;
>  			info->sd.node = node;
> -			info->sd.companion = root->device;
>  			bus = acpi_pci_root_create(root, &acpi_pci_root_ops,
>  						   &info->common, &info->sd);
>  		}
> @@ -373,21 +371,6 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  	return bus;
>  }
>  
> -int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
> -{
> -	/*
> -	 * We pass NULL as parent to pci_create_root_bus(), so if it is not NULL
> -	 * here, pci_create_root_bus() has been called by someone else and
> -	 * sysdata is likely to be different from what we expect.  Let it go in
> -	 * that case.
> -	 */
> -	if (!bridge->dev.parent) {
> -		struct pci_sysdata *sd = bridge->bus->sysdata;
> -		ACPI_COMPANION_SET(&bridge->dev, sd->companion);
> -	}
> -	return 0;
> -}
> -
>  int __init pci_acpi_init(void)
>  {
>  	struct pci_dev *dev = NULL;
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index ae3fe4e..4581e0e 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -564,6 +564,11 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  		}
>  	}
>  
> +	/*
> +	 * pci_create_root_bus() needs to detect the parent device type,
> +	 * so initialize its companion data accordingly.
> +	 */
> +	ACPI_COMPANION_SET(&device->dev, device);

This is a complete nonsense, sorry.

This just means that the ACPI firmware object will now be an ACPI companion of
itself.

Thanks,
Rafael