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SubjectRe: [PATCH] ACPI / PCI: Set root bridge ACPI handle in advance
From
On Sun, Dec 16, 2012 at 2:25 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> The ACPI handles of PCI root bridges need to be known to
> acpi_bind_one(), so that it can create the appropriate
> "firmware_node" and "physical_node" files for them, but currently
> the way it gets to know those handles is not exactly straightforward
> (to put it lightly).
>
> This is how it works, roughly:
>
> 1. acpi_bus_scan() finds the handle of a PCI root bridge,
> creates a struct acpi_device object for it and passes that
> object to acpi_pci_root_add().
>
> 2. acpi_pci_root_add() creates a struct acpi_pci_root object,
> populates its "device" field with its argument's address
> (device->handle is the ACPI handle found in step 1).
>
> 3. The struct acpi_pci_root object created in step 2 is passed
> to pci_acpi_scan_root() and used to get resources that are
> passed to pci_create_root_bus().
>
> 4. pci_create_root_bus() creates a struct pci_host_bridge object
> and passes its "dev" member to device_register().
>
> 5. platform_notify(), which for systems with ACPI is set to
> acpi_platform_notify(), is called.
>
> So far, so good. Now it starts to be "interesting".
>
> 6. acpi_find_bridge_device() is used to find the ACPI handle of
> the given device (which is the PCI root bridge) and executes
> acpi_pci_find_root_bridge(), among other things, for the
> given device object.
>
> 7. acpi_pci_find_root_bridge() uses the name (sic!) of the given
> device object to extract the segment and bus numbers of the PCI
> root bridge and passes them to acpi_get_pci_rootbridge_handle().
>
> 8. acpi_get_pci_rootbridge_handle() browses the list of ACPI PCI
> root bridges and finds the one that matches the given segment
> and bus numbers. Its handle is then used to initialize the
> ACPI handle of the PCI root bridge's device object by
> acpi_bind_one(). However, this is *exactly* the ACPI handle we
> started with in step 1.
>
> Needless to say, this is quite embarassing, but it may be avoided
> thanks to commit f3fd0c8 (ACPI: Allow ACPI handles of devices to be
> initialized in advance), which makes it possible to initialize the
> ACPI handle of a device before passing it to device_register().
> Namely, if pci_acpi_scan_root() could easily pass the root bridge's
> ACPI handle to pci_create_root_bus(), the latter could set the ACPI
> handle in its struct pci_host_bridge object's "dev" member before
> passing it to device_register() and steps 6-8 above wouldn't be
> necessary any more.
>
> To make that happen I decided to repurpose the 4th argument of
> pci_create_root_bus(), because that allowed me to avoid defining
> additional callbacks or similar things and didn't seem to impact
> architectures without ACPI substantially.
>
> Only x86 and ia64 are affected directly, there should be no
> functional changes resulting from this on other architectures.

that is good one to avoid that find_root_bridge...

>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> Should apply to the current Linus' tree, boots correctly on x86(-64).



>
> Thanks,
> Rafael
>
> ---
> arch/ia64/pci/pci.c | 5 ++++-
> arch/powerpc/kernel/pci-common.c | 3 ++-
> arch/sparc/kernel/pci.c | 3 ++-
> arch/x86/pci/acpi.c | 5 ++++-
> drivers/acpi/pci_root.c | 18 ------------------
> drivers/pci/pci-acpi.c | 19 -------------------
> drivers/pci/probe.c | 16 +++++++++++-----
> include/acpi/acpi_bus.h | 1 -
> include/linux/pci.h | 9 ++++++++-
> 9 files changed, 31 insertions(+), 48 deletions(-)

you need to update other arch for pci_create_root_bus

arch/powerpc/kernel/pci-common.c: bus =
pci_create_root_bus(hose->parent, hose->first_busno,
arch/s390/pci/pci.c: zdev->bus = pci_create_root_bus(NULL,
ZPCI_BUS_NR, &pci_root_ops,
arch/sparc/kernel/pci.c: bus = pci_create_root_bus(parent,
pbm->pci_first_busno, pbm->pci_ops,
drivers/parisc/dino.c: dino_dev->hba.hba_bus = bus =
pci_create_root_bus(&dev->dev,
drivers/parisc/lba_pci.c: pci_create_root_bus(&dev->dev,
lba_dev->hba.bus_num.start,


>
> Index: linux/arch/x86/pci/acpi.c
> ===================================================================
> --- linux.orig/arch/x86/pci/acpi.c
> +++ linux/arch/x86/pci/acpi.c
> @@ -450,6 +450,7 @@ struct pci_bus * __devinit pci_acpi_scan
> LIST_HEAD(resources);
> struct pci_bus *bus = NULL;
> struct pci_sysdata *sd;
> + struct pci_root_sys_info si;
> int node;
> #ifdef CONFIG_ACPI_NUMA
> int pxm;
> @@ -486,6 +487,8 @@ struct pci_bus * __devinit pci_acpi_scan
> sd = &info->sd;
> sd->domain = domain;
> sd->node = node;
> + si.acpi_node.handle = device->handle;
> + si.sysdata = sd;

maybe you can try to have si.acpi_handle directly ?

Yinghai


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