linux-kernel - [PATCH v1 1/2] PCI/portdrv: Set PCIE_PORT_SERVICE

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Date:   Mon, 21 Nov 2022 19:15:18 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Lukas Wunner <lukas@...ner.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH v1 1/2] PCI/portdrv: Set PCIE_PORT_SERVICE_HP for Root and Downstream Ports only

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

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 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 and so when
get_port_device_capability() runs, it sees that is_hotplug_bridge is
set and adds PCIE_PORT_SERVICE_HP to Port services (which allows pciehp
to bind to the Port in question) without consulting the PCIe type which
should be either Root Port or Downstream Port for the hotplug capability
to be present.

Make get_port_device_capability() more robust by adding a PCIe type
check to it before adding PCIE_PORT_SERVICE_HP to Port services which
helps to avoid the problem.

Reported-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
Suggested-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/pci/pcie/portdrv_core.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-pm/drivers/pci/pcie/portdrv_core.c
===================================================================
--- linux-pm.orig/drivers/pci/pcie/portdrv_core.c
+++ linux-pm/drivers/pci/pcie/portdrv_core.c
@@ -209,6 +209,8 @@ static int get_port_device_capability(st
 	int services = 0;

 	if (dev->is_hotplug_bridge &&
+	    (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
+	     pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM) &&
 	    (pcie_ports_native || host->native_pcie_hotplug)) {
 		services |= PCIE_PORT_SERVICE_HP;