PCI legacy resource fix

Since commit 368c73d4f689dae0807d0a2aa74c61fd2b9b075f the kernel will try
to update the non-writeable BAR registers 0..3 of PIIX4 IDE adapters if
pci_assign_unassigned_resources() is used to do full resource assignment of
the bus.  This fails because in the PIIX4 these BAR registers have
implicitly assumed values and read back as zero; it used to work because
the kernel used to just write zero to that register the read back value did
match what was written.

The fix is a new resource flag IORESOURCE_PCI_FIXED used to mark a resource
as non-movable.  This will also be useful to keep other import system
resources from being moved around - for example system consoles on PCI
busses.

[akpm@osdl.org: cleanup]
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 17 insertions, 2 deletions

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index ab78e4b..cb4ced3 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -33,11 +33,22 @@ pci_update_resource(struct pci_dev *dev, struct resource *res, int resno)
 	u32 new, check, mask;
 	int reg;
 
-	/* Ignore resources for unimplemented BARs and unused resource slots
-	   for 64 bit BARs. */
+	/*
+	 * Ignore resources for unimplemented BARs and unused resource slots
+	 * for 64 bit BARs.
+	 */
 	if (!res->flags)
 		return;
 
+	/*
+	 * Ignore non-moveable resources.  This might be legacy resources for
+	 * which no functional BAR register exists or another important
+	 * system resource we should better not move around in system address
+	 * space.
+	 */
+	if (res->flags & IORESOURCE_PCI_FIXED)
+		return;
+
 	pcibios_resource_to_bus(dev, &region, res);
 
 	pr_debug("  got res [%llx:%llx] bus [%lx:%lx] flags %lx for "
@@ -212,6 +223,10 @@ pdev_sort_resources(struct pci_dev *dev, struct resource_list *head)
 		resource_size_t r_align;
 
 		r = &dev->resource[i];
+
+		if (r->flags & IORESOURCE_PCI_FIXED)
+			continue;
+
 		r_align = r->end - r->start;
 		
 		if (!(r->flags) || r->parent)