[RFC PATCH 07/16] PCI: Separate pci_host_bridge creation out of pci_create_root_bus()

Yijing Wang
2014-11-19T02:24:52Z

>> We need, some platforms pass NULL pointer as host bridge parent.
>
> Yijing,
>
> May I suggest a different approach here? Rather than having to pass an opaque
> pointer that gets converted by the host bridge driver back to the private
> structure, what about promoting a new style of usage, that is similar to the
> way device drivers work? Lets try to promote the embedding of the generic
> pci_host_bridge structure in the host bridge specific structure! Then we can
> access the private data doing container_of().
>
> Something like this:
>
> struct pci_controller {
> struct pci_host_bridge bridge;
> /* private host bridge data here */
> .....
> };
>
> #define PCI_CONTROLLER(bus) ({
> struct pci_host_bridge *hb = to_pci_host_bridge(bus->bridge); \
> container_of(hb, struct pci_controller, bridge); })
>
>
> Then we can retrieve the host bridge structure from everywhere we have a device.

Hi Liviu, it looks good to me, because this change will involve lots platforms,
I would think more about it. Thanks for your suggestion very much! :)

Thanks!
Yijing.

>
> Best regards,
> Liviu
>
>>
>>>
>>>> + host = kzalloc(sizeof(*host), GFP_KERNEL);
>>>> + if (!host)
>>>> + return NULL;
>>>
>>> devm_kzalloc maybe?
>>
>> I don't know much detail about devm_kzalloc(), but we have no pci host driver
>> here, and I found no devm_kzalloc() uses in core PCI code before.
>>
>>>
>>>> + if (!resources) {
>>>> + /* Use default IO/MEM/BUS resources*/
>>>> + pci_add_resource(&host->windows, &ioport_resource);
>>>> + pci_add_resource(&host->windows, &iomem_resource);
>>>> + pci_add_resource(&host->windows, &busn_resource);
>>>> + } else {
>>>> + list_for_each_entry_safe(window, n, resources, list)
>>>> + list_move_tail(&window->list, &host->windows);
>>>> + }
>>>
>>> I think we should assume that the correct resources are passed. You
>>> could add a wrapper around this function to convert old platforms
>>> though.
>>
>> OK, I will move these code out of pci_create_host_bridge, and add a wrapper
>> to setup the default resources.
>>
>>>
>>>> +EXPORT_SYMBOL(pci_create_host_bridge);
>>>
>>> EXPORT_SYMBOL_GPL() maybe?
>>
>> OK, will update it.
>>
>>>
>>>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>>>> index 8b11b38..daa7f40 100644
>>>> --- a/include/linux/pci.h
>>>> +++ b/include/linux/pci.h
>>>> @@ -402,7 +402,12 @@ struct pci_host_bridge_window {
>>>> struct pci_host_bridge {
>>>> struct device dev;
>>>> struct pci_bus *bus; /* root bus */
>>>> + struct list_head list;
>>>> struct list_head windows; /* pci_host_bridge_windows */
>>>> + int busnum;
>>>
>>> The busnum should already be implied through the bus resource.
>>
>> Yes, I will consider remove it and introduce a helper function to get the root bus number, thanks!
>>
>> Thanks!
>> Yijing.
>>
>>>
>>> Arnd
>>>
>>> .
>>>
>>
>>
>> --
>> Thanks!
>> Yijing
>>
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>

--
Thanks!
Yijing