From c63a3be76df678b173c59f1d5dc19a21b2d1c753 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 21 Nov 2022 19:16:57 +0100 Subject: PCI: acpiphp: Avoid setting is_hotplug_bridge for PCIe Upstream Ports It is reported that on some systems pciehp binds to an Upstream Port and attempts to operate it which causes devices below the Port to disappear from the bus. This happens because acpiphp sets dev->is_hotplug_bridge for that Port (after receiving a Device Check notification on it from the platform firmware via ACPI) during the enumeration of PCI devices. get_port_device_capability() sees that dev->is_hotplug_bridge is set and adds PCIE_PORT_SERVICE_HP to Port services, which allows pciehp to bind to the Port in question. Even though this particular problem can be addressed by making the portdrv_core checks more robust, it also causes power management to work differently on the affected systems which generally is not desirable (PCIe Ports with dev->is_hotplug_bridge set have to pass additional tests to be allowed to go into the D3hot/cold power states which affects runtime PM of devices below these Ports). For this reason, amend check_hotplug_bridge() with a PCIe type check to prevent it from setting dev->is_hotplug_bridge for Upstream Ports. Suggested-by: Lukas Wunner Link: https://lore.kernel.org/r/2262230.ElGaqSPkdT@kreacher Reported-by: Rodrigo Vivi Tested-by: Rodrigo Vivi Signed-off-by: Rafael J. Wysocki Signed-off-by: Bjorn Helgaas Reviewed-by: Rodrigo Vivi Reviewed-by: Lukas Wunner --- drivers/pci/hotplug/acpiphp_glue.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/pci/hotplug/acpiphp_glue.c') diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 6efa3d8db9a5..5b1f271c6034 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -411,6 +411,14 @@ static void check_hotplug_bridge(struct acpiphp_slot *slot, struct pci_dev *dev) if (dev->is_hotplug_bridge) return; + /* + * In the PCIe case, only Root Ports and Downstream Ports are capable of + * accommodating hotplug devices, so avoid marking Upstream Ports as + * "hotplug bridges". + */ + if (pci_is_pcie(dev) && pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM) + return; + list_for_each_entry(func, &slot->funcs, sibling) { if (PCI_FUNC(dev->devfn) == func->function) { dev->is_hotplug_bridge = 1; -- cgit v1.2.3