Hi Rafael,
Thanks for your great efforts to review the patch.
On 01/09/2013 08:01 AM, Rafael J. Wysocki wrote:
> Hi,
>
> On Wednesday, January 09, 2013 12:52:22 AM Jiang Liu wrote:
snip
>>
>> +static void acpi_pci_slot_notify_add(struct pci_dev *dev)
>> +{
>> + acpi_handle handle;
>> + struct callback_args context;
>> +
>> + if (!dev->subordinate)
>> + return;
>> +
>> + mutex_lock(&slot_list_lock);
>> + handle = DEVICE_ACPI_HANDLE(&dev->dev);
>> + context.root_handle = acpi_find_root_bridge_handle(dev);
>
> There's a patch under discussion that removes this function.
>
> Isn't there any other way to do this?
I will try to find a way to get rid of calling acpi_find_root_bridge_handle,
and it seems doable.
>
>> + if (handle && context.root_handle) {
>> + context.pci_bus = dev->subordinate;
>> + context.user_function = register_slot;
>> + acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
>
> You can just pass 1 here I think. Does the compiler complain?
Thanks for reminder, the (u32) is unnecessary.
>
>> + register_slot, NULL, &context, NULL);
>> + }
>> + mutex_unlock(&slot_list_lock);
>> +}
>> +
>> +static void acpi_pci_slot_notify_del(struct pci_dev *dev)
>> +{
>> + struct acpi_pci_slot *slot, *tmp;
>> + struct pci_bus *bus = dev->subordinate;
>> +
>> + if (!bus)
>> + return;
>> +
>> + mutex_lock(&slot_list_lock);
>> + list_for_each_entry_safe(slot, tmp, &slot_list, list)
>> + if (slot->pci_slot && slot->pci_slot->bus == bus) {
>> + list_del(&slot->list);
>> + pci_destroy_slot(slot->pci_slot);
>> + put_device(&bus->dev);
>> + kfree(slot);
>> + }
>> + mutex_unlock(&slot_list_lock);
>> +}
>> +
>> +static int acpi_pci_slot_notify_fn(struct notifier_block *nb,
>> + unsigned long event, void *data)
>> +{
>> + struct device *dev = data;
>> +
>> + switch (event) {
>> + case BUS_NOTIFY_ADD_DEVICE:
>> + acpi_pci_slot_notify_add(to_pci_dev(dev));
>> + break;
>
> Do I think correctly that this is going to be called for every PCI device
> added to the system, even if it's not a bridge?
You are right. Function acpi_pci_slot_notify_add() and acpi_pci_slot_notify_del()
will check whether it's a bridge. If preferred, I will move the check up into
acpi_pci_slot_notify_fn().
>
>> + case BUS_NOTIFY_DEL_DEVICE:
>> + acpi_pci_slot_notify_del(to_pci_dev(dev));
>> + break;
>> + default:
>> + return NOTIFY_DONE;
>> + }
>> +
>> + return NOTIFY_OK;
>> +}
>> +
>> +static struct notifier_block acpi_pci_slot_notifier = {
>> + .notifier_call = &acpi_pci_slot_notify_fn,
>> +};
>> +
>> static int __init
>> acpi_pci_slot_init(void)
>> {
>> dmi_check_system(acpi_pci_slot_dmi_table);
>> acpi_pci_register_driver(&acpi_pci_slot_driver);
>> + bus_register_notifier(&pci_bus_type, &acpi_pci_slot_notifier);
>
> I wonder if/why this has to be so convoluted?
>
> We have found a PCI bridge in the ACPI namespace, so we've created a struct
> acpi_device for it and we've walked the namespace below it already.
>
> Now we're creating a struct pci_dev for it and while registering it we're
> going to walk the namespace below the bridge again to find and register its
> slots and that is done indirectly from a bus type notifier.
>
> Why can't we enumerate the slots directly upfront?
Do you mean to create the PCI slot devices when creating the ACPI devices?
I think there are two factors prevent us from doing that.
The first is that the ACPI pci_slot driver could be built as a module, so
we can't call into it from the ACPI core.
The second reason is that the PCI slot is associated with a PCI bus, and the
bus is only available until the PCI device has been created.
Thanks!
Gerry
>
>> +
>> return 0;
>> }
>>
>> static void __exit
>> acpi_pci_slot_exit(void)
>> {
>> + bus_unregister_notifier(&pci_bus_type, &acpi_pci_slot_notifier);
>> acpi_pci_unregister_driver(&acpi_pci_slot_driver);
>> }
>
> Thanks,
> Rafael
>
>
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