On 01/13/2013 07:34 AM, Rafael J. Wysocki wrote:
> On Friday, January 11, 2013 02:40:38 PM Yinghai Lu wrote:
>> From: Jiang Liu <jiang.liu@xxxxxxxxxx>
>>
>> The code in pci_root_hp.c depends on function acpi_is_root_bridge()
>> to check whether an ACPI object is a PCI host bridge or not.
>> If an ACPI device hasn't been created for the ACPI object yet,
>> function acpi_is_root_bridge() will return false even if the object
>> is a PCI host bridge object. That behavior will cause two issues:
>> 1) No ACPI notification handler installed for PCI host bridges absent
>> at startup, so hotplug events for those bridges won't be handled.
>> 2) rescan_root_bridge() can't reenumerate offlined PCI host bridges
>> because the ACPI devices have been already destroyed.
>>
>> So use acpi_match_object_info_ids() to correctly detect PCI host bridges.
>>
>> -v2: update to use acpi_match_object_info_ids() from Tang Chen - Yinghai
>> -v3: drop the PNP0A008, according to Bjorn.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
>> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
>> Cc: Len Brown <lenb@xxxxxxxxxx>
>> Cc: linux-acpi@xxxxxxxxxxxxxxx
>> ---
>> drivers/acpi/pci_root.c | 19 ++++++++++++++++++-
>> 1 file changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index 5ae36d8..d30fb94 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -923,6 +923,23 @@ static void handle_hotplug_event_root(acpi_handle handle, u32 type,
>> _handle_hotplug_event_root);
>> }
>>
>> +static bool acpi_is_root_bridge_object(acpi_handle handle)
>> +{
>> + struct acpi_device_info *info = NULL;
>> + acpi_status status;
>> + bool ret;
>> +
>> + status = acpi_get_object_info(handle, &info);
>> + if (ACPI_FAILURE(status))
>> + return false;
>> +
>> + ret = !acpi_match_object_info_ids(info, root_device_ids);
>> +
>
> Well, I kind of don't understand why don't we check info->flags
> against ACPI_PCI_ROOT_BRIDGE that acpi_get_object_info() sets for us if it
> finds a PCI root bridge?
Hi Rafael,
Thanks for reminder, we should test ACPI_PCI_ROOT_BRIDGE flag
instead of a redundant calling to acpi_match_object_info_ids(). To be honest,
I don't know the existence of ACPI_PCI_ROOT_BRIDGE flag before:(
>
>> + kfree(info);
>> +
>> + return ret;
>> +}
>> +
>> static acpi_status __init
>> find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
>> {
>> @@ -931,7 +948,7 @@ find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
>> .pointer = objname };
>> int *count = (int *)context;
>>
>> - if (!acpi_is_root_bridge(handle))
>> + if (!acpi_is_root_bridge_object(handle))
>> return AE_OK;
>>
>> (*count)++;
>>
>
> Thanks,
> Rafael
>
>
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