Re: [openib-general] Re: mthca and LinuxBIOS

[Ivan Kokshaysky <ink@jurassic.park.msu.ru>]

On Fri, Aug 05, 2005 at 09:33:54PM -0700, Grant Grundler wrote:
> > ISTR making comments before about the offending patch on linux-pci mailing
> > list.  Is this the same patch that assumes pci_dev->resource[i] == BAR[i] ?
> 
> I meant the patch assume 1:1 for pci_dev->resource[i] and BAR[i].
> not that the two are equivalent.

This is correct assumption. For 64-bit BAR[i] only pci_dev->resource[i] is
valid, pci_dev->resource[i+1] slot is unused and contains zeroes in all
fields. So all we need is just to check that we're going to update a _valid_
resource.
[Though, if we ever want to support >4Gb bus allocations on 32-bit
architectures we need to make resource start and end fields u64.]

Ivan.

--- 2.6.13-rc5-git4/drivers/pci/setup-res.c	Sun Aug  7 12:08:23 2005
+++ linux/drivers/pci/setup-res.c	Sun Aug  7 13:27:54 2005
@@ -33,6 +33,11 @@ pci_update_resource(struct pci_dev *dev,
 	u32 new, check, mask;
 	int reg;
 
+	/* Ignore resources for unimplemented BARs and unused resource slots
+	   for 64 bit BARs. */
+	if (!res->flags)
+		return;
+
 	pcibios_resource_to_bus(dev, &region, res);
 
 	pr_debug("  got res [%lx:%lx] bus [%lx:%lx] flags %lx for "
@@ -67,7 +72,7 @@ pci_update_resource(struct pci_dev *dev,
 
 	if ((new & (PCI_BASE_ADDRESS_SPACE|PCI_BASE_ADDRESS_MEM_TYPE_MASK)) ==
 	    (PCI_BASE_ADDRESS_SPACE_MEMORY|PCI_BASE_ADDRESS_MEM_TYPE_64)) {
-		new = 0; /* currently everyone zeros the high address */
+		new = region.start >> 32;
 		pci_write_config_dword(dev, reg + 4, new);
 		pci_read_config_dword(dev, reg + 4, &check);
 		if (check != new) {