On 08/14/2012 05:51 PM, Stephen Warren wrote: > On 08/14/2012 04:58 PM, Stephen Warren wrote: >> On 08/14/2012 03:55 PM, Bjorn Helgaas wrote: >>> On Tue, Aug 14, 2012 at 12:58 PM, Thierry Reding >>> <thierry.reding@xxxxxxxxxxxxxxxxx> wrote: >>>> On Tue, Aug 14, 2012 at 01:39:23PM -0600, Stephen Warren wrote: >>>>> On 08/13/2012 05:18 PM, Bjorn Helgaas wrote: >>>>>> On Mon, Aug 13, 2012 at 11:47 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: >>>>> ... >>>>>>> whereas for a device tree boot: >>>>>>> >>>>>>> (same): >>>>>>>> [ 2.112217] pci 0000:01:00.0: reg 10: [io 0x0000-0x00ff] >>>>>>>> [ 2.117635] pci 0000:01:00.0: reg 18: [mem 0x00000000-0x00000fff 64bit pref] >>>>>>>> [ 2.124690] pci 0000:01:00.0: reg 20: [mem 0x00000000-0x00003fff 64bit pref] >>>>>>>> [ 2.131731] pci 0000:01:00.0: reg 30: [mem 0x00000000-0x0001ffff pref] >>>>>>> ... (request region happens early) >>>>>>>> [ 2.179838] r8169 0000:01:00.0: BAR 0: requesting [io 0x0000-0x00ff] >>>>>>>> [ 2.193312] r8169 0000:01:00.0: BAR 2: requesting [mem 0x00000000-0x00000fff 64bit pref] >>>>>>>> [ 2.201397] r8169 0000:01:00.0: BAR 2: can't reserve [mem 0x00000000-0x00000fff 64bit pref] >>>>>>>> [ 2.209742] r8169 0000:01:00.0: (unregistered net_device): could not request regions >>>>>>> ... (same, just happens too late) >>>>>>>> [ 2.236818] pci 0000:01:00.0: BAR 6: assigned [mem 0xa0000000-0xa001ffff pref] >>>>>>>> [ 2.244027] pci 0000:01:00.0: BAR 4: assigned [mem 0xa0020000-0xa0023fff 64bit pref] >>>>>>>> [ 2.251794] pci 0000:01:00.0: BAR 2: assigned [mem 0xa0024000-0xa0024fff 64bit pref] >>>>>>>> [ 2.259542] pci 0000:01:00.0: BAR 0: assigned [io 0x1000-0x10ff] >>>>>>> >>>>>>> I suspect this is all still related to the PCI devices themselves being >>>>>>> probed much earlier in the overall PCI initialization sequence when the >>>>>>> PCI controller is probed later in the boot sequence, whereas PCI device >>>>>>> probe is deferred until the overall PCI initialization sequence is >>>>>>> complete if the PCI controller is probed very early in the boot sequence. >>>>>> >>>>>> I don't know what to apply your patches to (they don't apply cleanly >>>>>> to v3.6-rc2), so I can't see exactly what you're doing. But it looks >>>>>> like you might be calling pci_bus_add_devices() before >>>>>> pci_bus_assign_resource(), which isn't going to work. >>>>> >>>>> Yes, that's exactly what is happening. >>>>> >>>>> PCIe initialization starts in arch/arm/mach-tegra/pci.e >>>>> tegra_pcie_init() which calls arch/arm/kernel/bios32.c >>>>> pci_common_init(). That function first calls pcibios_init_hw() (in the >>>>> same file, more about this later) and then loops over PCI buses, calling >>>>> amongst other things pci_bus_assign_resources() then pci_bus_add_devices(). >>>>> >>>>> The problem is that ARM's pcibios_init_hw() calls pci_scan_root_bus() >>>>> (or a host-driver-specific function which that also calls >>>>> pci_scan_root_bus() in Tegra's case) which in turn calls >>>>> pci_bus_add_devices() right at the end, before control has returned to >>>>> pci_common_init() and hence before pci_bus_assign_resources() has been >>>>> called. >>>>> >>>>> If I modify pci_scan_root_bus() and remove the call to >>>>> pci_bus_add_devices(), everything works as expected. >>>>> >>>>> So, I guess the question is: Should ARM's pcibios_init_hw() not be >>>>> calling pci_scan_root_bus(), or at least presumably the ARM PCI code >>>>> needs to do things in a slightly different order? >>> >>> I think you need to do something like this instead of using pci_scan_root_bus(): >>> >>> pci_create_root_bus() >>> pci_scan_child_bus() >>> pci_bus_assign_resources() >>> pci_bus_add_devices() >>> >>> This is the effective order used by most of the pci_create_root_bus() callers. >> >> That would pretty much duplicate everything in pci_scan_root_bus(). That >> might cause divergence down the road. >> >> Can't we make the call to pci_bus_add_devices() optional in >> pci_scan_root_bus() somehow; one of: > > Sigh, that turns out not to work correctly; it solves at least this part > of the problem when booting using device tree, but when booting using a > board file, it causes the IRQ number passed to the PCIe device to be > bogus:-( The reason this fails is because the following happens after pci_scan_bus_root(): pci_fixup_irqs(pcibios_swizzle, pcibios_map_irq); (in arch/arm/kernel/bios32.c:pci_common_init()) So, if I replace the call to pci_scan_root_bus() with the code you wrote above, then the IRQ numbers aren't assigned into the pci_dev structures until after they're device_add()ed, and hence probed(). Ideally, I could just add a call to pci_fixup_irqs() right before the call to pci_bus_add_devices() in the code you wrote above. However, that won't work, because pci_fixup_irqs() finds all the PCI devices to fix up by searching the list of devices that pci_bus_add_devices() adds to:-( I guess it's a pretty basic premise of the current PCI code that all the PCI scanning happens well before any device drivers are registered, which in turn means that device_add() doesn't trigger the device's probe() until much later, after all the fixups and resource assignments are done? -- 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
