On Tue, Feb 13, 2018 at 5:31 PM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> When a system is using native PCIe hotplug for Thunderbolt and the
> controller is not enabled for full RTD3 (runtime D3) it will be only
> present in the system when there is a device connected. This pretty much
> follows the BIOS assisted hotplug behaviour.
>
> Thunderbolt host controller integrated PCIe switch has two additional
> PCIe downstream ports that lead to NHI (Thunderbolt host controller) and
> xHCI (USB 3 host controller) respectively. These downstream ports are
> not marked being hotplug capable. Reason for that is to preserve
> resources. Otherwise the OS would distribute remaining resources between
> all downstream ports making these two ports consume too much resources
> they don't really need (both NHI and xHCI only need 1 MB of MMIO space,
> and no extra buses).
>
> Now, because these ports are not marked being hotplug capable the OS
> will not enable hotplug interrupt for them either and will not receive
> interrupt when devices below them are hotplugged. Solution to this is
> that the BIOS sends ACPI Notify() for the root port to notify the OS it
> needs to rescan for added devices.
>
> However, the current ACPI hotplug implementation scans the whole slot
> regardless whether native PCIe is used or not and it expects that the
> BIOS has configured bridge resources upfront. If that's not the case it
> assigns resources using minimal allocation (everything currently found
> just barely fit) preventing future extension. In addition to that, if
> there is another native PCIe hotplug going on we may find the new PCIe
> switch only partially ready (all links are not fully trained yet)
> confusing PCIehp when it finally starts to enumerate new devices.
>
> To make this work better with the native PCIe hotplug driver (PCIehp),
> we let it to handle all slot management and resource allocation for
> hotplug bridges and restrict ACPI hotplug to non-hotplug bridges.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/pci/hotplug/acpiphp.h | 1 +
> drivers/pci/hotplug/acpiphp_glue.c | 73 ++++++++++++++++++++++++++++++--------
> 2 files changed, 59 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pci/hotplug/acpiphp.h b/drivers/pci/hotplug/acpiphp.h
> index e438a2d734f2..8dcfd623ef1d 100644
> --- a/drivers/pci/hotplug/acpiphp.h
> +++ b/drivers/pci/hotplug/acpiphp.h
> @@ -158,6 +158,7 @@ struct acpiphp_attention_info
>
> #define SLOT_ENABLED (0x00000001)
> #define SLOT_IS_GOING_AWAY (0x00000002)
> +#define SLOT_IS_NATIVE (0x00000004)
>
> /* function flags */
>
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index b45b375c0e6c..5efa21cdddc9 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -282,6 +282,9 @@ static acpi_status acpiphp_add_context(acpi_handle handle, u32 lvl, void *data,
> slot->device = device;
> INIT_LIST_HEAD(&slot->funcs);
>
> + if (pdev && pciehp_is_native(pdev))
> + slot->flags |= SLOT_IS_NATIVE;
> +
> list_add_tail(&slot->node, &bridge->slots);
>
> /*
> @@ -291,7 +294,7 @@ static acpi_status acpiphp_add_context(acpi_handle handle, u32 lvl, void *data,
> * expose slots to user space in those cases.
> */
> if ((acpi_pci_check_ejectable(pbus, handle) || is_dock_device(adev))
> - && !(pdev && pdev->is_hotplug_bridge && pciehp_is_native(pdev))) {
> + && !(slot->flags & SLOT_IS_NATIVE && pdev->is_hotplug_bridge)) {
> unsigned long long sun;
> int retval;
>
> @@ -430,6 +433,29 @@ static int acpiphp_rescan_slot(struct acpiphp_slot *slot)
> return pci_scan_slot(slot->bus, PCI_DEVFN(slot->device, 0));
> }
>
> +static void acpiphp_native_scan_bridge(struct pci_dev *bridge)
> +{
> + struct pci_bus *bus = bridge->subordinate;
> + struct pci_dev *dev;
> + int max;
> +
> + if (!bus)
> + return;
> +
> + max = bus->busn_res.start;
> + /* Scan already configured non-hotplug bridges */
> + for_each_pci_bridge(dev, bus) {
> + if (!dev->is_hotplug_bridge)
> + max = pci_scan_bridge(bus, dev, max, 0);
> + }
> +
> + /* Scan non-hotplug bridges that need to be reconfigured */
> + for_each_pci_bridge(dev, bus) {
> + if (!dev->is_hotplug_bridge)
> + max = pci_scan_bridge(bus, dev, max, 1);
> + }
> +}
> +
> /**
> * enable_slot - enable, configure a slot
> * @slot: slot to be enabled
> @@ -442,25 +468,42 @@ static void enable_slot(struct acpiphp_slot *slot)
> struct pci_dev *dev;
> struct pci_bus *bus = slot->bus;
> struct acpiphp_func *func;
> - int max, pass;
> - LIST_HEAD(add_list);
>
> - acpiphp_rescan_slot(slot);
> - max = acpiphp_max_busnr(bus);
> - for (pass = 0; pass < 2; pass++) {
> + if (slot->flags & SLOT_IS_NATIVE) {
> + /*
> + * If native PCIe hotplug is used, it will take care of
> + * hotplug slot management and resource allocation for
> + * hotplug bridges. However, ACPI hotplug may still be
> + * used for non-hotplug bridges to bring in additional
> + * devices such as Thunderbolt host controller.
> + */
> for_each_pci_bridge(dev, bus) {
> - if (PCI_SLOT(dev->devfn) != slot->device)
> - continue;
> -
> - max = pci_scan_bridge(bus, dev, max, pass);
> - if (pass && dev->subordinate) {
> - check_hotplug_bridge(slot, dev);
> - pcibios_resource_survey_bus(dev->subordinate);
> - __pci_bus_size_bridges(dev->subordinate, &add_list);
> + if (PCI_SLOT(dev->devfn) == slot->device)
> + acpiphp_native_scan_bridge(dev);
> + }
> + pci_assign_unassigned_bridge_resources(bus->self);
> + } else {
> + LIST_HEAD(add_list);
> + int max, pass;
> +
> + acpiphp_rescan_slot(slot);
> + max = acpiphp_max_busnr(bus);
> + for (pass = 0; pass < 2; pass++) {
> + for_each_pci_bridge(dev, bus) {
> + if (PCI_SLOT(dev->devfn) != slot->device)
> + continue;
> +
> + max = pci_scan_bridge(bus, dev, max, pass);
> + if (pass && dev->subordinate) {
> + check_hotplug_bridge(slot, dev);
> + pcibios_resource_survey_bus(dev->subordinate);
> + __pci_bus_size_bridges(dev->subordinate,
> + &add_list);
> + }
> }
> }
> + __pci_bus_assign_resources(bus, &add_list, NULL);
> }
> - __pci_bus_assign_resources(bus, &add_list, NULL);
>
> acpiphp_sanitize_bus(bus);
> pcie_bus_configure_settings(bus);
> --
> 2.15.1
>
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