[PATCH 2/3] Do not use acpi_device to find pci root bridge in _init code.

From: Tang Chen
Date: Fri Oct 12 2012 - 06:33:04 EST


When the kernel is being initialized, and some hardwares are not added
to system, there won't be acpi_device structs for these devices. But
acpi_is_root_bridge() depends on acpi_device struct. As a result, all
the not-added root bridge will not be judged as a root bridge in
find_root_bridges(). And further more, no handle_hotplug_event_root()
notifier will be installed for them.

This patch introduces a new api to find all root bridges in system by
getting HID directly from ACPI namespace, not depending on acpi_device
struct.

Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
---
drivers/acpi/pci_root.c | 27 ++++++++++++++++++++++-----
1 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 7d0fb03..3819bee 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -128,9 +128,6 @@ EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);
/**
* acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
* @handle - the ACPI CA node in question.
- *
- * Note: we could make this API take a struct acpi_device * instead, but
- * for now, it's more convenient to operate on an acpi_handle.
*/
int acpi_is_root_bridge(acpi_handle handle)
{
@@ -138,8 +135,28 @@ int acpi_is_root_bridge(acpi_handle handle)
struct acpi_device *device;

ret = acpi_bus_get_device(handle, &device);
- if (ret)
- return 0;
+ if (ret) {
+ /**
+ * If a device is not added to the system yet, there won't be
+ * an acpi_device struct for it. But it doesn't mean it is not
+ * a PCI root bridge. In this case we need to get HID and CID
+ * from ACPI namespace directly.
+ */
+ struct acpi_device_info *info;
+ acpi_status status;
+ status = acpi_get_object_info(handle, &info);
+ if (ACPI_FAILURE(status)) {
+ printk(KERN_ERR PREFIX "%s: Error reading"
+ "device info\n", __func__);
+ return 0;
+ }
+
+ ret = acpi_match_object_info_ids(info, root_device_ids);
+ if (ret)
+ return 0;
+ else
+ return 1;
+ }

ret = acpi_match_device_ids(device, root_device_ids);
if (ret)
--
1.7.1

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