diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 24d86bd1bba1f82fd5528681da0e641046d1cfd8..9839d6f9bcb5defa200c995b5c96ccaa3dee1a2d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1004,15 +1004,10 @@ static void __pci_start_power_transition(struct pci_dev *dev, pci_power_t state)
 	if (state == PCI_D0) {
 		pci_platform_power_transition(dev, PCI_D0);
 		/*
-		 * Mandatory power management transition delays, see
-		 * PCI Express Base Specification Revision 2.0 Section
-		 * 6.6.1: Conventional Reset.  Do not delay for
-		 * devices powered on/off by corresponding bridge,
-		 * because have already delayed for the bridge.
+		 * Mandatory power management transition delays are
+		 * handled in the PCIe portdrv resume hooks.
 		 */
 		if (dev->runtime_d3cold) {
-			if (dev->d3cold_delay && !dev->imm_ready)
-				msleep(dev->d3cold_delay);
 			/*
 			 * When powering on a bridge from D3cold, the
 			 * whole hierarchy may be powered on into
@@ -4579,14 +4574,16 @@ static int pci_pm_reset(struct pci_dev *dev, int probe)
 
 	return pci_dev_wait(dev, "PM D3->D0", PCIE_RESET_READY_POLL_MS);
 }
+
 /**
- * pcie_wait_for_link - Wait until link is active or inactive
+ * pcie_wait_for_link_delay - Wait until link is active or inactive
  * @pdev: Bridge device
  * @active: waiting for active or inactive?
+ * @delay: Delay to wait after link has become active (in ms)
  *
  * Use this to wait till link becomes active or inactive.
  */
-bool pcie_wait_for_link(struct pci_dev *pdev, bool active)
+bool pcie_wait_for_link_delay(struct pci_dev *pdev, bool active, int delay)
 {
 	int timeout = 1000;
 	bool ret;
@@ -4623,13 +4620,25 @@ bool pcie_wait_for_link(struct pci_dev *pdev, bool active)
 		timeout -= 10;
 	}
 	if (active && ret)
-		msleep(100);
+		msleep(delay);
 	else if (ret != active)
 		pci_info(pdev, "Data Link Layer Link Active not %s in 1000 msec\n",
 			active ? "set" : "cleared");
 	return ret == active;
 }
 
+/**
+ * pcie_wait_for_link - Wait until link is active or inactive
+ * @pdev: Bridge device
+ * @active: waiting for active or inactive?
+ *
+ * Use this to wait till link becomes active or inactive.
+ */
+bool pcie_wait_for_link(struct pci_dev *pdev, bool active)
+{
+	return pcie_wait_for_link_delay(pdev, active, 100);
+}
+
 void pci_reset_secondary_bus(struct pci_dev *dev)
 {
 	u16 ctrl;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index e04fa7fd3e2f0ad8b7241ee2199a6c1dd1769ced..7f9fd93270eda3a7863bc9ca8d3a3e62ba4a8082 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -494,6 +494,7 @@ static inline int pci_dev_specific_disable_acs_redir(struct pci_dev *dev)
 void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state,
 		      u32 service);
 
+bool pcie_wait_for_link_delay(struct pci_dev *pdev, bool active, int delay);
 bool pcie_wait_for_link(struct pci_dev *pdev, bool active);
 #ifdef CONFIG_PCIEASPM
 void pcie_aspm_init_link_state(struct pci_dev *pdev);
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index 1b330129089fea765919e7ae477298473edb843c..308c3e0c4a34012ebda42d5e86d342c8a42edd68 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/kernel.h>
+#include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
@@ -378,6 +379,67 @@ static int pm_iter(struct device *dev, void *data)
 	return 0;
 }
 
+static int get_downstream_delay(struct pci_bus *bus)
+{
+	struct pci_dev *pdev;
+	int min_delay = 100;
+	int max_delay = 0;
+
+	list_for_each_entry(pdev, &bus->devices, bus_list) {
+		if (!pdev->imm_ready)
+			min_delay = 0;
+		else if (pdev->d3cold_delay < min_delay)
+			min_delay = pdev->d3cold_delay;
+		if (pdev->d3cold_delay > max_delay)
+			max_delay = pdev->d3cold_delay;
+	}
+
+	return max(min_delay, max_delay);
+}
+
+/*
+ * wait_for_downstream_link - Wait for downstream link to establish
+ * @pdev: PCIe port whose downstream link is waited
+ *
+ * Handle delays according to PCIe 4.0 section 6.6.1 before configuration
+ * access to the downstream component is permitted.
+ *
+ * This blocks PCI core resume of the hierarchy below this port until the
+ * link is trained. Should be called before resuming port services to
+ * prevent pciehp from starting to tear-down the hierarchy too soon.
+ */
+static void wait_for_downstream_link(struct pci_dev *pdev)
+{
+	int delay;
+
+	if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT &&
+	    pci_pcie_type(pdev) != PCI_EXP_TYPE_DOWNSTREAM)
+		return;
+
+	if (pci_dev_is_disconnected(pdev))
+		return;
+
+	if (!pdev->subordinate || list_empty(&pdev->subordinate->devices) ||
+	    !pdev->bridge_d3)
+		return;
+
+	delay = get_downstream_delay(pdev->subordinate);
+	if (!delay)
+		return;
+
+	dev_dbg(&pdev->dev, "waiting downstream link for %d ms\n", delay);
+
+	/*
+	 * If downstream port does not support speeds greater than 5 GT/s
+	 * need to wait 100ms. For higher speeds (gen3) we need to wait
+	 * first for the data link layer to become active.
+	 */
+	if (pcie_get_speed_cap(pdev) <= PCIE_SPEED_5_0GT)
+		msleep(delay);
+	else
+		pcie_wait_for_link_delay(pdev, true, delay);
+}
+
 /**
  * pcie_port_device_suspend - suspend port services associated with a PCIe port
  * @dev: PCI Express port to handle
@@ -391,6 +453,8 @@ int pcie_port_device_suspend(struct device *dev)
 int pcie_port_device_resume_noirq(struct device *dev)
 {
 	size_t off = offsetof(struct pcie_port_service_driver, resume_noirq);
+
+	wait_for_downstream_link(to_pci_dev(dev));
 	return device_for_each_child(dev, &off, pm_iter);
 }
 
@@ -421,6 +485,8 @@ int pcie_port_device_runtime_suspend(struct device *dev)
 int pcie_port_device_runtime_resume(struct device *dev)
 {
 	size_t off = offsetof(struct pcie_port_service_driver, runtime_resume);
+
+	wait_for_downstream_link(to_pci_dev(dev));
 	return device_for_each_child(dev, &off, pm_iter);
 }
 #endif /* PM */