Re: [PATCH 01/28] PCI: Rip out pci_bus_add_devices() from pci_scan_bus()

Yijing Wang
2015-01-19T02:04:34Z

On 2015/1/17 7:16, Yinghai Lu wrote:
> On Fri, Jan 16, 2015 at 3:15 PM, Yinghai Lu <yinghai@kernel.org> wrote:
>> On Thu, Jan 15, 2015 at 5:43 PM, Yijing Wang <wangyijing@huawei.com> wrote:
>>> Pci_bus_add_devices() should not be placed in pci_scan_bus().
>>> Now pci device will be added to driver core once its
>>> creation. All things left in pci_bus_add_devices() are
>>> driver attachment and other trivial sysfs things.
>>> Pci_scan_bus() should be the function responsible for
>>> scanning PCI devices, not including driver attachment.
>>> Other, some callers(m68k,unicore32,alpha) of pci_scan_bus()
>>> will call pci_bus_size_bridges() and pci_bus_assign_resources()
>>> after pci_scan_bus().
>>>
>>> E.g.
>>> In m68k
>>> mcf_pci_init()
>>> pci_scan_bus()
>>> ...
>>> pci_bus_add_devices() --- try to attach driver
>>> pci_fixup_irqs()
>>> pci_bus_size_bridges()
>>> pci_bus_assign_resources()
>>>
>>> It is not correct, resources should be assigned correctly
>>> before attaching driver.
>>
> No, for booting path, at that time pci drivers are *NOT* loaded yet.

Hi Yinghai, I knew code flow here would not cause problems, sorry the log
confused you, I will refresh it. But I think pci_scan_bus()/pci_scan_root_bus()
which could only be used during system boot up(before module_init) make
the pci scan logic obscure. Because most callers additionally call
pci_bus_size_bridges() and pci_bus_assign_resources() later,
so rip out pci_bus_add_devices() from pci_scan_bus()/pci_scan_root_bus()
make code have better readability.

Thanks!
Yijing.

>
> Thanks
>
> Yinghai
>
> .
>

--
Thanks!
Yijing