Re: [PATCH 6/6] x86/PCI: quirk Thunderbolt PCI-to-PCI bridges

[Yinghai Lu]

On Wed, Jun 26, 2013 at 3:55 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> On Wed, Jun 26, 2013 at 4:31 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>> On Wed, Jun 26, 2013 at 3:26 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>>> On Wed, Jun 26, 2013 at 3:18 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>>>> On Tue, Jun 25, 2013 at 10:22 AM, Mika Westerberg
>>>> <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
>>>>> Thunderbolt PCI-to-PCI bridges typically use BIOS "assisted" enumeration.
>>>>> This means that the BIOS will allocate bridge resources based on some
>>>>> assumptions of a maximum Thunderbolt chain. It also disables native PCIe
>>>>> hotplug of the root port where the Thunderbolt host router is connected.
>> ...
>> During acpi hotplug, firmare could do extra help for us like assign
>> some resources to pci device bars, so it is NOT "boot-time".
>
> Really?  How can firmware assign BARs at hotplug-time?  I mean,
> obviously firmware *can* write things to the BARs before giving the
> device to the OS, but how would it know what to write?

should be acpi code, or SMI code or even BMC firmware via sideband.

>  I assume the
> OS owns the address space, and it can change the upstream bridge
> windows or the BARs of another device on the bus at any time, subject
> to the OS's own issues as far as quiescing or unbinding drivers, etc.,
> but without coordinating with the BIOS.

for thunderbolt or dock with acpiphp, then all children devices/bridges should
not have drivers loaded yet.

Yinghai
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/