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....@huawei.com>
> Reported-by: Alexander E. Patrakov <patra...@gmail.com>
> Tested-by: Alexander E. Patrakov <patra...@gmail.com>
> Cc: "Rafael J. Wysocki" <r...@sisk.pl>
> Cc: linux-a...@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: <sta...@vger.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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