Re: Continuing PCI and Yenta troubles in 2.6.13.1 and 2.6.14-rc1

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

On Tue, Sep 20, 2005 at 12:02:23PM +0200, Andreas Koch wrote:
> Thus, I believe there is still something rotten in the PCI code since the 
> 2.6.12-rc6 days.

Thanks a lot for the report.

You are right, and I believe the change that broke things is
introduction of pci_fixup_parent_subordinate_busnr()...

The patch here does two things:
- hunk #1 should fix the problems you've seen when you boot without
  additional "pci" kernel options;
- hunk #2 supposedly fixes boot with "pci=assign-busses" option which
  otherwise hangs Acer TM81xx machines as reported.

Please try this with and without "pci=assign-busses". If it boots,
I'd like to see 'lspci -vvx' for both cases.

Ivan.

--- 2.6.13.2/drivers/pci/probe.c	Mon Aug  8 12:20:28 2005
+++ linux/drivers/pci/probe.c	Tue Sep 20 16:17:23 2005
@@ -400,6 +400,12 @@ static void pci_enable_crs(struct pci_de
 static void __devinit pci_fixup_parent_subordinate_busnr(struct pci_bus *child, int max)
 {
 	struct pci_bus *parent = child->parent;
+
+	/* Attempts to fix that up are really dangerous unless
+	   we're going to re-assign all bus numbers. */
+	if (!pcibios_assign_all_busses())
+		return;
+
 	while (parent->parent && parent->subordinate < max) {
 		parent->subordinate = max;
 		pci_write_config_byte(parent->self, PCI_SUBORDINATE_BUS, max);
@@ -476,8 +482,18 @@ int __devinit pci_scan_bridge(struct pci
 		 * We need to assign a number to this bus which we always
 		 * do in the second pass.
 		 */
-		if (!pass)
+		if (!pass) {
+			if (pcibios_assign_all_busses())
+				/* Temporarily disable forwarding of the
+				   configuration cycles on all bridges in
+				   this bus segment to avoid possible
+				   conflicts in the second pass between two
+				   bridges programmed with overlapping
+				   bus ranges. */
+				pci_write_config_dword(dev, PCI_PRIMARY_BUS,
+						       buses & ~0xffffff);
 			return max;
+		}
 
 		/* Clear errors */
 		pci_write_config_word(dev, PCI_STATUS, 0xffff);