[PATCH] PCI: Improve PCI config space writeback

At least one laptop blew up on resume from suspend with a black screen due to a lack of this patch. By only writing back config space that is different, we minimise the possibility of accidents like this. Signed-off-by: Dave Jones <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
ambv · Jun 11, 2006 · 04d9c1a · 04d9c1a
1 parent 8d92bc2
commit 04d9c1a
Showing 1 changed file with 13 additions and 3 deletions.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
@@ -461,9 +461,19 @@ int
 pci_restore_state(struct pci_dev *dev)
 {
 	int i;
-
-	for (i = 0; i < 16; i++)
-		pci_write_config_dword(dev,i * 4, dev->saved_config_space[i]);
+	int val;
+
+	for (i = 0; i < 16; i++) {
+		pci_read_config_dword(dev, i * 4, &val);
+		if (val != dev->saved_config_space[i]) {
+			printk(KERN_DEBUG "PM: Writing back config space on "
+				"device %s at offset %x (was %x, writing %x)\n",
+				pci_name(dev), i,
+				val, (int)dev->saved_config_space[i]);
+			pci_write_config_dword(dev,i * 4,
+				dev->saved_config_space[i]);
+		}
+	}
 	pci_restore_msi_state(dev);
 	pci_restore_msix_state(dev);
 	return 0;