diff -bur linux-4.15-patched/drivers/pci/pci.c linux-4.15/drivers/pci/pci.c
--- linux-4.15-patched/drivers/pci/pci.c	2018-03-04 21:12:43.927969009 -0800
+++ linux-4.15/drivers/pci/pci.c	2018-03-04 21:20:14.972944154 -0800
@@ -1112,12 +1112,12 @@
 EXPORT_SYMBOL(pci_save_state);
 
 static void pci_restore_config_dword(struct pci_dev *pdev, int offset,
-				     u32 saved_val, int retry)
+				     u32 saved_val, int retry, int force)
 {
 	u32 val;
 
 	pci_read_config_dword(pdev, offset, &val);
-	if (val == saved_val)
+	if (!force && val == saved_val)
 		return;
 
 	for (;;) {
@@ -1136,33 +1136,29 @@
 }
 
 static void pci_restore_config_space_range(struct pci_dev *pdev,
-					   int start, int end, int retry)
+					   int start, int end, int retry, int force)
 {
 	int index;
 
 	for (index = end; index >= start; index--)
 		pci_restore_config_dword(pdev, 4 * index,
 					 pdev->saved_config_space[index],
-					 retry);
+					 retry, force);
 }
 
-static void pci_restore_config_space(struct pci_dev *pdev)
+static void pci_restore_config_space(struct pci_dev *pdev, int force)
 {
 	if (pdev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
-		pci_restore_config_space_range(pdev, 10, 15, 0);
+		pci_restore_config_space_range(pdev, 10, 15, 0, force);
 		/* Restore BARs before the command register. */
-		pci_restore_config_space_range(pdev, 4, 9, 10);
-		pci_restore_config_space_range(pdev, 0, 3, 0);
+		pci_restore_config_space_range(pdev, 4, 9, 10, force);
+		pci_restore_config_space_range(pdev, 0, 3, 0, force);
 	} else {
-		pci_restore_config_space_range(pdev, 0, 15, 0);
+		pci_restore_config_space_range(pdev, 0, 15, 0, force);
 	}
 }
 
-/**
- * pci_restore_state - Restore the saved state of a PCI device
- * @dev: - PCI device that we're dealing with
- */
-void pci_restore_state(struct pci_dev *dev)
+static void _pci_restore_state(struct pci_dev *dev, int force)
 {
 	if (!dev->state_saved)
 		return;
@@ -1176,7 +1172,7 @@
 
 	pci_cleanup_aer_error_status_regs(dev);
 
-	pci_restore_config_space(dev);
+	pci_restore_config_space(dev, force);
 
 	pci_restore_pcix_state(dev);
 	pci_restore_msi_state(dev);
@@ -1187,6 +1183,15 @@
 
 	dev->state_saved = false;
 }
+
+/**
+ * pci_restore_state - Restore the saved state of a PCI device
+ * @dev: - PCI device that we're dealing with
+ */
+void pci_restore_state(struct pci_dev *dev)
+{
+	_pci_restore_state(dev, 0);
+}
 EXPORT_SYMBOL(pci_restore_state);
 
 struct pci_saved_state {
@@ -4083,6 +4088,8 @@
 {
 	u16 ctrl;
 
+	pci_save_state(dev);
+
 	pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &ctrl);
 	ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
@@ -4092,10 +4099,23 @@
 	 */
 	msleep(2);
 
+	pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &ctrl);
 	ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
 
 	/*
+	 * According to PCI-to-PCI Bridge Architecture Specification 3.2.5.17
+	 *
+	 * "The bridge’s secondary bus interface and any buffers between
+	 * the two interfaces (primary and secondary) must be initialized
+	 * back to their default state whenever this bit is set."
+	 *
+	 * Failure to observe this causes inability to access devices on the
+	 * secondary bus on the AMD Threadripper platform.
+	 */
+	_pci_restore_state(dev, 1);
+
+	/*
 	 * Trhfa for conventional PCI is 2^25 clock cycles.
 	 * Assuming a minimum 33MHz clock this results in a 1s
 	 * delay before we can consider subordinate devices to
diff -bur linux-4.15-patched/include/linux/pci.h linux-4.15/include/linux/pci.h
--- linux-4.15-patched/include/linux/pci.h	2018-03-04 21:12:43.808969015 -0800
+++ linux-4.15/include/linux/pci.h	2018-03-04 21:28:17.950917540 -0800
@@ -1640,7 +1640,8 @@
 
 /* Power management related routines */
 static inline int pci_save_state(struct pci_dev *dev) { return 0; }
-static inline void pci_restore_state(struct pci_dev *dev) { }
+void pci_restore_state(struct pci_dev *dev) { }
+static inline void _pci_restore_state(struct pci_dev *dev, int force) { }
 static inline int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
 { return 0; }
 static inline int pci_wake_from_d3(struct pci_dev *dev, bool enable)