Re: Please revert 928bea964827d7824b548c1f8e06eccbbc4d0d7d

Yinghai Lu
2013-09-27T17:44:47Z

On Fri, Sep 27, 2013 at 9:01 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Fri, Sep 27, 2013 at 1:28 AM, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
>> Hi Linus, Yinghai !
>>
>> Please consider reverting:
>>
>> 928bea964827d7824b548c1f8e06eccbbc4d0d7d
>> PCI: Delay enabling bridges until they're needed
>>
>> (I'd suggest to revert now and maybe merge a better patch later)
>>
>> This breaks PCI on the PowerPC "powernv" platform (which is booted via
>> kexec) and probably x86 as well under similar circumstances. It will
>> basically break PCIe if the bus master bit of the bridge isn't set at
>> boot (by the firmware for example, or because kexec'ing cleared it).
>>
>> The reason is that the PCIe port driver will call pci_enable_device() on
>> the bridge (on everything under the sun actually), which will marked the
>> device enabled (but will not do a set_master).
>>
>> Because of that, pci_enable_bridge() later on (called as a result of the
>> child device driver doing pci_enable_device) will see the bridge as
>> already enabled and will not call pci_set_master() on it.

Ben,

looks like PCIe port driver does call pci_enable_device AND pci_set_master()

| int pcie_port_device_register(struct pci_dev *dev)
| {
| int status, capabilities, i, nr_service;
| int irqs[PCIE_PORT_DEVICE_MAXSERVICES];
|
| /* Enable PCI Express port device */
| status = pci_enable_device(dev);
| if (status)
| return status;
|
| /* Get and check PCI Express port services */
| capabilities = get_port_device_capability(dev);
| if (!capabilities)
| return 0;
|
| pci_set_master(dev);

so how come that pci_set_master is not called for powerpc?

Can you send out lspci -vvxxx with current linus-tree and v3.11?

Yinghai