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    SubjectRe: [Alternative][PATCH] ACPI / PCI: Set root bridge ACPI handle in advance, v2
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    On Wed, Jan 9, 2013 at 3:06 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
    > On Wednesday, January 09, 2013 03:16:59 PM Bjorn Helgaas wrote:
    >> On Wed, Jan 9, 2013 at 2:33 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().
    >> >
    >> > Accordingly, add a new __weak routine, pcibios_root_bridge_prepare(),
    >> > defaulting to an empty implementation that can be replaced by the
    >> > interested architecutres (x86 and ia64 at the moment) with functions
    >> > that will set the root bridge's ACPI handle before its dev member is
    >> > passed to device_register(). Make both x86 and ia64 provide such
    >> > implementations of pcibios_root_bridge_prepare() and remove
    >> > acpi_pci_find_root_bridge() and acpi_get_pci_rootbridge_handle() that
    >> > aren't necessary any more.
    >> >
    >> > Included is a fix for breakage on systems with non-ACPI PCI host
    >> > bridges from Bjorn Helgaas.
    >> >
    >> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >>
    >> Looks good to me!
    >>
    >> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
    >
    > Thanks!
    >
    > I'll wait for comments from the others, if any, and put it into my acpi-scan
    > branch after a couple of days. It doesn't need to be there technically, but
    > it's kind of related.

    I tested it with acpi-scan and pci-root-bus-hotplug patchset, and it works well.
    so
    Acked-by: Yinghai Lu <yinghai@kernel.org>

    BTW, found one left over of change about ->acpi_handle==> ACPI_HANDLE..

    Index: linux-2.6/drivers/acpi/glue.c
    ===================================================================
    --- linux-2.6.orig/drivers/acpi/glue.c
    +++ linux-2.6/drivers/acpi/glue.c
    @@ -311,7 +311,7 @@ static int acpi_platform_notify(struct d
    if (!ret) {
    struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

    - acpi_get_name(dev->acpi_handle, ACPI_FULL_PATHNAME, &buffer);
    + acpi_get_name(ACPI_HANDLE(dev), ACPI_FULL_PATHNAME, &buffer);
    DBG("Device %s -> %s\n", dev_name(dev), (char *)buffer.pointer);
    kfree(buffer.pointer);
    } else

    otherwise will get compiling error when enable acpi glue debug.

    Thanks

    Yinghai


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