[PATCH v6 09/11] PCI: Put PCIe bridges with downstream devices into D3 at hibernate

["Mario Limonciello (AMD)" <superm1@kernel.org>]

For the suspend flow PCIe bridges that have downstream devices are put into
the appropriate low power state (D3hot or D3cold depending upon specific
devices). For the hibernate flow, PCIe bridges with downstream devices
stay in D0 however. This can lead to PCIe bridges that are remained
powered on needlessly during hibernate.

Adjust the pci_pm_poweroff_noirq() to follow the same flow as
pci_pm_suspend_noirq() by using pci_pm_suspend_noirq_common().

This introduces a functional change that the hibernate flow will now
call pci_save_state() and unless bus PM is skipped will also set
the PCIe device into an unknown state.

Cc: AceLan Kao <acelan.kao@canonical.com>
Cc: Kai-Heng Feng <kaihengf@nvidia.com>
Cc: Mark Pearson <mpearson-lenovo@squebb.ca>
Cc: Denis Benato <benato.denis96@gmail.com>
Cc: Merthan Karakaş <m3rthn.k@gmail.com>
Tested-by: Eric Naim <dnaim@cachyos.org>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
v6:
 * s/port/bridge/
v5:
 * Split out into more patches
 * Rewrite commit
 * Add tag
v4:
 * Use helper even when CONFIG_SUSPEND not set (LKP robot)
 * https://lore.kernel.org/linux-pci/20250616175019.3471583-1-superm1@kernel.org/
v3:
 * Split out common code between suspend_noirq() and poweroff_noirq()
   to a helper function
 * https://lore.kernel.org/linux-pm/20250609024619.407257-1-superm1@kernel.org/T/#me6db0fb946e3d604a8f3d455128844ed802c82bb
---
 drivers/pci/pci-driver.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index c563fd6af979d..5eedfbb0be8a4 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -762,7 +762,7 @@ static void pci_pm_complete(struct device *dev)
 
 #endif /* !CONFIG_PM_SLEEP */
 
-#if defined(CONFIG_SUSPEND)
+#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATE_CALLBACKS)
 /**
  * pci_pm_suspend_noirq_common
  * @pci_dev: pci device
@@ -808,7 +808,7 @@ static void pci_pm_suspend_noirq_common(struct pci_dev *pci_dev, bool *skip_bus_
 
 	pci_pm_set_unknown_state(pci_dev);
 }
-#endif /* CONFIG_SUSPEND */
+#endif /* CONFIG_SUSPEND || CONFIG_HIBERNATE_CALLBACKS */
 
 #ifdef CONFIG_SUSPEND
 static void pcie_pme_root_status_cleanup(struct pci_dev *pci_dev)
@@ -1164,6 +1164,8 @@ static int pci_pm_poweroff(struct device *dev)
 	    (system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF))
 		device_set_wakeup_enable(dev, false);
 
+	pci_dev->skip_bus_pm = false;
+
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_suspend(dev, PMSG_HIBERNATE);
 
@@ -1206,6 +1208,7 @@ static int pci_pm_poweroff_noirq(struct device *dev)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+	bool skip_bus_pm = false;
 
 	if (dev_pm_skip_suspend(dev))
 		return 0;
@@ -1227,8 +1230,9 @@ static int pci_pm_poweroff_noirq(struct device *dev)
 			return error;
 	}
 
-	if (!pci_dev->state_saved && pci_power_manageable(pci_dev))
-		pci_prepare_to_sleep(pci_dev);
+	pci_pm_suspend_noirq_common(pci_dev, &skip_bus_pm);
+	if (skip_bus_pm)
+		goto Fixup;
 
 	/*
 	 * The reason for doing this here is the same as for the analogous code
@@ -1237,6 +1241,7 @@ static int pci_pm_poweroff_noirq(struct device *dev)
 	if (pci_dev->class == PCI_CLASS_SERIAL_USB_EHCI)
 		pci_write_config_word(pci_dev, PCI_COMMAND, 0);
 
+Fixup:
 	pci_fixup_device(pci_fixup_suspend_late, pci_dev);
 
 	return 0;
-- 
2.43.0