On Tue, Aug 27, 2013 at 5:43 PM, Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: > On Tue, Aug 27, 2013 at 03:34:11PM -0600, Bjorn Helgaas wrote: >> [+cc Stefan] >> >> On Mon, Aug 26, 2013 at 9:39 AM, Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: >> > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed >> > slots for hotplug capabilites got reversed. While this isn't a big deal, it did >> > uncover a bug in the ACPI bus setup path. Specifically, acpi_pci_root_add calls >> > pci_acpi_scan_root before setting the osc flags for the device handle. >> > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp() >> > to determine if a given slot has pcie hotplug capabilties, whcih checks the >> > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag. Since that flag is not set >> > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie >> > slots are hotplug capable and configures them all to use acpi instead. >> >> I'd like to make it more explicit what we're fixing. Apparently this >> is a regression between v3.9 and v3.10. >> >> Is this a fix for problems like >> https://bugzilla.kernel.org/show_bug.cgi?id=60736 ? That bug is that >> an ExpressCard slot doesn't work unless we boot with >> "acpiphp.disable=1". I think what happens there is that acpiphp >> claims the slot before we run _OSC, so pciehp doesn't claim it, even >> though _OSC did grant us control over native PCIe hotplug. >> > Yes, that bug is precisely what I am trying to fix (although your wording above is > inverted from the problem in the bug). What happens is that acpiphp claims the > pcie ports, because acpiphp init runs first, and we haven't yet parsed _OSC, > which would have told acpiphp to yield control to pciehp. The initial fix I > proposed fixed this by parsing _OSC prior to running the acpiphp bus scan, but > that reintroduced the problem of not handling pcie 1.1 aspm properly. That has > been fixed in v2/v3 by deferring the setting of aspm_disable until after the bus > scan. > > Shall I submit a v4 with an updated changelog? No need, I'll update the changelog and include the bugzilla reference and post it for your approval. Thanks! Bjorn -- 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
