PCI/PM: Skip resuming to D0 if device is disconnected

When a device is surprise-removed (e.g., due to a dock unplug), the PCI
core unconfigures all downstream devices and sets their error state to
pci_channel_io_perm_failure. This marks them as disconnected via
pci_dev_is_disconnected().

During device removal, the runtime PM framework may attempt to resume the
device to D0 via pm_runtime_get_sync(), which calls into pci_power_up().
Since the device is already disconnected, this resume attempt is
unnecessary and results in a predictable errors like this, typically when
undocking from a TBT3 or USB4 dock with PCIe tunneling:

  pci 0000:01:00.0: Unable to change power state from D3cold to D0, device inaccessible

Avoid powering up disconnected devices by checking their status early in
pci_power_up() and returning -EIO.

Suggested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
[bhelgaas: add typical message]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://patch.msgid.link/20250909031916.4143121-1-superm1@kernel.org

Author: superm1

drivers/pci/pci.c

@@ -1374,6 +1374,11 @@ int pci_power_up(struct pci_dev *dev)
 		return -EIO;
 	}
 
+	if (pci_dev_is_disconnected(dev)) {
+		dev->current_state = PCI_D3cold;
+		return -EIO;
+	}
+
 	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
 	if (PCI_POSSIBLE_ERROR(pmcsr)) {
 		pci_err(dev, "Unable to change power state from %s to D0, device inaccessible\n",