1 files changed, 51 insertions, 2 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index c9d8e3c837de..13d65991c77b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1233,7 +1233,6 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
 	pcie_capability_write_word(dev, PCI_EXP_SLTCTL2, cap[i++]);
 }
 
-
 static int pci_save_pcix_state(struct pci_dev *dev)
 {
 	int pos;
@@ -1270,6 +1269,45 @@ static void pci_restore_pcix_state(struct pci_dev *dev)
 	pci_write_config_word(dev, pos + PCI_X_CMD, cap[i++]);
 }
 
+static void pci_save_ltr_state(struct pci_dev *dev)
+{
+	int ltr;
+	struct pci_cap_saved_state *save_state;
+	u16 *cap;
+
+	if (!pci_is_pcie(dev))
+		return;
+
+	ltr = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!ltr)
+		return;
+
+	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state) {
+		pci_err(dev, "no suspend buffer for LTR; ASPM issues possible after resume\n");
+		return;
+	}
+
+	cap = (u16 *)&save_state->cap.data[0];
+	pci_read_config_word(dev, ltr + PCI_LTR_MAX_SNOOP_LAT, cap++);
+	pci_read_config_word(dev, ltr + PCI_LTR_MAX_NOSNOOP_LAT, cap++);
+}
+
+static void pci_restore_ltr_state(struct pci_dev *dev)
+{
+	struct pci_cap_saved_state *save_state;
+	int ltr;
+	u16 *cap;
+
+	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
+	ltr = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_LTR);
+	if (!save_state || !ltr)
+		return;
+
+	cap = (u16 *)&save_state->cap.data[0];
+	pci_write_config_word(dev, ltr + PCI_LTR_MAX_SNOOP_LAT, *cap++);
+	pci_write_config_word(dev, ltr + PCI_LTR_MAX_NOSNOOP_LAT, *cap++);
+}
 
 /**
  * pci_save_state - save the PCI configuration space of a device before suspending
@@ -1291,6 +1329,7 @@ int pci_save_state(struct pci_dev *dev)
 	if (i != 0)
 		return i;
 
+	pci_save_ltr_state(dev);
 	pci_save_dpc_state(dev);
 	return pci_save_vc_state(dev);
 }
@@ -1390,7 +1429,12 @@ void pci_restore_state(struct pci_dev *dev)
 	if (!dev->state_saved)
 		return;
 
-	/* PCI Express register must be restored first */
+	/*
+	 * Restore max latencies (in the LTR capability) before enabling
+	 * LTR itself (in the PCIe capability).
+	 */
+	pci_restore_ltr_state(dev);
+
 	pci_restore_pcie_state(dev);
 	pci_restore_pasid_state(dev);
 	pci_restore_pri_state(dev);
@@ -2998,6 +3042,11 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
 	if (error)
 		pci_err(dev, "unable to preallocate PCI-X save buffer\n");
 
+	error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_LTR,
+					    2 * sizeof(u16));
+	if (error)
+		pci_err(dev, "unable to allocate suspend buffer for LTR\n");
+
 	pci_allocate_vc_save_buffers(dev);
 }