linux-kernel - Re: [BUGFIX v2 4/4] ACPIPHP: fix bug 56531 Sony VAIO VPCZ23A4R: can't assign mem/io after docking

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Date:	Mon, 17 Jun 2013 13:57:44 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jiang Liu <jiang.liu@...wei.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yinghai Lu <yinghai@...nel.org>,
	"Alexander E . Patrakov" <patrakov@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Yijing Wang <wangyijing@...wei.com>,
	linux-acpi@...r.kernel.org, Jiang Liu <liuj97@...il.com>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [BUGFIX v2 4/4] ACPIPHP: fix bug 56531 Sony VAIO VPCZ23A4R: can't assign mem/io after docking

On Saturday, June 15, 2013 03:28:01 AM Jiang Liu wrote:
> Please refer to https://bugzilla.kernel.org/show_bug.cgi?id=56531 for
> more information.
> 
> This issue is caused by differences in PCI resource assignment between
> boot time and runtime hotplug. On x86 platforms, OS respects PCI
> resource assignment from BIOS and only reassign resources for unassigned
> BARs at boot time. But with acpiphp, it ignores BIOS resource assignment
> and reassign all resources by itself.
> 
> If we have enough resources, reassigning all PCI resources should work
> too, but it may fail if we are under resource constraints. On the other
> handle, current PCI MMIO alignment algorithm may waste huge MMIO address
> space if we have some PCI devices with huge MMIO BARs.
> 
> On this Sony laptop, BIOS allocates limited MMIO resources for the dock
> station and the dock station has a gfx which has a 256MB MMIO BAR.
> So current acpiphp driver fails to allocate resources for most devices
> on the dock station.
> 
> So change acpiphp driver to follow boot time behavior to respect BIOS
> resource assignment.
> 
> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
> Reported-by: Alexander E. Patrakov <patrakov@...il.com>
> Tested-by: Alexander E. Patrakov <patrakov@...il.com>
> Cc: "Rafael J. Wysocki" <rjw@...k.pl>
> Cc: linux-acpi@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: <stable@...r.kernel.org>

The code is fine as far as I'm concerned, but I have one request. ->

> ---
>  drivers/pci/hotplug/acpiphp_glue.c | 7 +++++--
>  drivers/pci/pci.h                  | 5 +++++
>  drivers/pci/setup-bus.c            | 8 ++++----
>  3 files changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index a65203b..f4a53e9 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -687,6 +687,7 @@ static int __ref enable_device(struct acpiphp_slot *slot)
>  	struct pci_bus *bus = slot->bridge->pci_bus;
>  	struct acpiphp_func *func;
>  	int num, max, pass;
> +	LIST_HEAD(add_list);
>  
>  	if (slot->flags & SLOT_ENABLED)
>  		goto err_exit;
> @@ -711,13 +712,15 @@ static int __ref enable_device(struct acpiphp_slot *slot)
>  				max = pci_scan_bridge(bus, dev, max, pass);
>  				if (pass && dev->subordinate) {
>  					check_hotplug_bridge(slot, dev);
> -					pci_bus_size_bridges(dev->subordinate);

Please add a comment explaining why we need to do this here.

> +					pcibios_resource_survey_bus(dev->subordinate);
> +					__pci_bus_size_bridges(dev->subordinate,
> +							       &add_list);
>  				}
>  			}
>  		}
>  	}
>  
> -	pci_bus_assign_resources(bus);
> +	__pci_bus_assign_resources(bus, &add_list, NULL);
>  	acpiphp_sanitize_bus(bus);
>  	acpiphp_set_hpp_values(bus);
>  	acpiphp_set_acpi_region(slot);
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 68678ed..d1182c4 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -202,6 +202,11 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
>  		    struct resource *res, unsigned int reg);
>  int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type);
>  void pci_configure_ari(struct pci_dev *dev);
> +void __ref __pci_bus_size_bridges(struct pci_bus *bus,
> +			struct list_head *realloc_head);
> +void __ref __pci_bus_assign_resources(const struct pci_bus *bus,
> +				      struct list_head *realloc_head,
> +				      struct list_head *fail_head);
>  
>  /**
>   * pci_ari_enabled - query ARI forwarding status
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 16abaaa..d254e23 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1044,7 +1044,7 @@ handle_done:
>  	;
>  }
>  
> -static void __ref __pci_bus_size_bridges(struct pci_bus *bus,
> +void __ref __pci_bus_size_bridges(struct pci_bus *bus,
>  			struct list_head *realloc_head)
>  {
>  	struct pci_dev *dev;
> @@ -1115,9 +1115,9 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
>  }
>  EXPORT_SYMBOL(pci_bus_size_bridges);
>  
> -static void __ref __pci_bus_assign_resources(const struct pci_bus *bus,
> -					 struct list_head *realloc_head,
> -					 struct list_head *fail_head)
> +void __ref __pci_bus_assign_resources(const struct pci_bus *bus,
> +				      struct list_head *realloc_head,
> +				      struct list_head *fail_head)
>  {
>  	struct pci_bus *b;
>  	struct pci_dev *dev;

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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