[PATCH v6] PCI/PM: Skip resuming to D0 if disconnected

[PATCH v6] PCI/PM: Skip resuming to D0 if disconnected

[Mario Limonciello (AMD)]

When a USB4 dock is unplugged the PCIe bridge it's connected to will
issue a "Link Down" and "Card not detected event". The PCI core will
treat this as a surprise hotplug event and unconfigure all downstream
devices. This involves setting the device error state to
`pci_channel_io_perm_failure` which pci_dev_is_disconnected() will check.

It doesn't make sense to runtime resume disconnected devices to D0 and
report the (expected) error, so bail early.

Suggested-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
v6:
 * rebase on v6.17-rc1
v5:
 * Pick up tags, rebase on linux-next
 * https://lore.kernel.org/linux-pci/20250709205948.3888045-1-superm1@kernel.org/T/#mbd784f786c50a3d1b5ab1833520995c01eae2fd2
---
 drivers/pci/pci.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b0f4d98036cdd..036511f5b2625 100644
--- a/drivers/pci/pci.c
+++ b/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",

base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
-- 
2.43.0