PCI: Retry BARs restoration for Type 0 headers only

Some shortcomings introduced into pci_restore_state() by commit
26f4106 ("PCI: check for pci bar restore completion and retry")
have been fixed by recent commit ebfc5b8 ("PCI: Fix regression in
pci_restore_state(), v3"), but that commit treats all PCI devices as
those with Type 0 configuration headers.

That is not entirely correct, because Type 1 and Type 2 headers have
different layouts.  In particular, the area occupied by BARs in Type 0
config headers contains the secondary status register in Type 1 ones and
it doesn't make sense to retry the restoration of that register even if
the value read back from it after a write is not the same as the written
one (it very well may be different).

For this reason, make pci_restore_state() only retry the restoration
of BARs for Type 0 config headers.  This effectively makes it behave
as before commit 26f4106 for all header types except for Type 0.

Tested-by: Mikko Vinni <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: rjwysocki

drivers/pci/pci.c

@@ -991,8 +991,8 @@ static void pci_restore_config_dword(struct pci_dev *pdev, int offset,
 	}
 }
 
-static void pci_restore_config_space(struct pci_dev *pdev, int start, int end,
-				     int retry)
+static void pci_restore_config_space_range(struct pci_dev *pdev,
+					   int start, int end, int retry)
 {
 	int index;
 
@@ -1002,6 +1002,18 @@ static void pci_restore_config_space(struct pci_dev *pdev, int start, int end,
 					 retry);
 }
 
+static void pci_restore_config_space(struct pci_dev *pdev)
+{
+	if (pdev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
+		pci_restore_config_space_range(pdev, 10, 15, 0);
+		/* Restore BARs before the command register. */
+		pci_restore_config_space_range(pdev, 4, 9, 10);
+		pci_restore_config_space_range(pdev, 0, 3, 0);
+	} else {
+		pci_restore_config_space_range(pdev, 0, 15, 0);
+	}
+}
+
 /** 
  * pci_restore_state - Restore the saved state of a PCI device
  * @dev: - PCI device that we're dealing with
@@ -1015,13 +1027,7 @@ void pci_restore_state(struct pci_dev *dev)
 	pci_restore_pcie_state(dev);
 	pci_restore_ats_state(dev);
 
-	pci_restore_config_space(dev, 10, 15, 0);
-	/*
-	 * The Base Address register should be programmed before the command
-	 * register(s)
-	 */
-	pci_restore_config_space(dev, 4, 9, 10);
-	pci_restore_config_space(dev, 0, 3, 0);
+	pci_restore_config_space(dev);
 
 	pci_restore_pcix_state(dev);
 	pci_restore_msi_state(dev);