On Thu, Jun 27, 2013 at 9:00 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: > On Wed, Jun 26, 2013 at 5:56 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: >> 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. > > How would that code (ACPI code (by which I assume you mean AML), SMI > code, BMC firmware) know what values to write to BARs? Is it reading > the windows of upstream bridges from config space? Is it assuming the > OS never changes the windows of bridges upstream from the Thunderbolt > controller? Kernel only try to change upstream bridge for pciehp during hot-add. for acpiphp, because could have other devices already there before hot-add, kernel does not try to expand the upstream bridge. size and assign only to the new added devices. > >>> 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. > > I said "upstream bridge windows or ... another device on the bus," > i.e., I'm referring to devices other than the Thunderbolt controller. > I assume the OS is free to change resource assignments for those > non-Thunderbolt devices, and obviously those assignments affect what > is available for Thunderbolt. ok. that upstream one can not be touched from firmware. -- 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
