PCI/ACPI: Account for _S0W of the target bridge in acpi_pci_bridge_d3()

It is questionable to allow a PCI bridge to go into D3 if it has _S0W
returning D2 or a shallower power state, so modify acpi_pci_bridge_d3(() to
always take the return value of _S0W for the target bridge into account.
That is, make it return 'false' if _S0W returns D2 or a shallower power
state for the target bridge regardless of its ancestor Root Port
properties.  Of course, this also causes 'false' to be returned if the Root
Port itself is the target and its _S0W returns D2 or a shallower power
state.

However, still allow bridges without _S0W that are power-manageable via
ACPI to enter D3 to retain the current code behavior in that case.

This fixes problems where a hotplug notification is missed because a bridge
is in D3.  That means hot-added devices such as USB4 docks (and the devices
they contain) and Thunderbolt 3 devices may not work.

Link: https://lore.kernel.org/linux-pci/20221031223356.32570-1-mario.limonciello@amd.com/
Link: https://lore.kernel.org/r/12155458.O9o76ZdvQC@kreacher
Reported-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 97450f4003cc..f007116a8427 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -484,6 +484,25 @@ void acpi_dev_power_up_children_with_adr(struct acpi_device *adev)
 	acpi_dev_for_each_child(adev, acpi_power_up_if_adr_present, NULL);
 }
 
+/**
+ * acpi_dev_power_state_for_wake - Deepest power state for wakeup signaling
+ * @adev: ACPI companion of the target device.
+ *
+ * Evaluate _S0W for @adev and return the value produced by it or return
+ * ACPI_STATE_UNKNOWN on errors (including _S0W not present).
+ */
+u8 acpi_dev_power_state_for_wake(struct acpi_device *adev)
+{
+	unsigned long long state;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(adev->handle, "_S0W", NULL, &state);
+	if (ACPI_FAILURE(status))
+		return ACPI_STATE_UNKNOWN;
+
+	return state;
+}
+
 #ifdef CONFIG_PM
 static DEFINE_MUTEX(acpi_pm_notifier_lock);
 static DEFINE_MUTEX(acpi_pm_notifier_install_lock);