On 19/01/15 12:04, Yijing Wang wrote: > On 2015/1/17 7:16, Yinghai Lu wrote: >> On Fri, Jan 16, 2015 at 3:15 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: >>> On Thu, Jan 15, 2015 at 5:43 PM, Yijing Wang <wangyijing@xxxxxxxxxx> 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. I agree that ordering seems odd. I recall there was a reason I had to put it in that order (at that time - which is a few years back now). I can't remember exactly now, but it was something like bridges didn't get resourced properly without a pci scan first. Regards Greg -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
