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Commit 49887941 authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Greg Kroah-Hartman
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[PATCH] PCI: use bus numbers sparsely, if necessary 



Add a warning if a child bus may be inaccessible because the
parent bridge has wrong secondary or subordinate bus numbers.
Note that this may or may not happen on "transparent" bridges,
as can be seen in bug #5557.

Also, if we do not fix up the assignment of bus numbers, try to
make use of the bus number space available.

Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 0eb3bcfd

drivers/pci/probe.c

+37 −2
Original line number Diff line number Diff line
@@ -433,7 +433,7 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max 
{

	struct pci_bus *child;

	int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);

	u32 buses, i;

	u32 buses, i, j = 0;

	u16 bctl;



	pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
@@ -543,10 +543,29 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max 
			 * as cards with a PCI-to-PCI bridge can be

			 * inserted later.

			 */

			for (i=0; i<CARDBUS_RESERVE_BUSNR; i++)

			for (i=0; i<CARDBUS_RESERVE_BUSNR; i++) {

				struct pci_bus *parent = bus;

				if (pci_find_bus(pci_domain_nr(bus),

							max+i+1))

					break;

				while (parent->parent) {

					if ((!pcibios_assign_all_busses()) &&

					    (parent->subordinate > max) &&

					    (parent->subordinate <= max+i)) {

						j = 1;

					}

					parent = parent->parent;

				}

				if (j) {

					/*

					 * Often, there are two cardbus bridges

					 * -- try to leave one valid bus number

					 * for each one.

					 */

					i /= 2;

					break;

				}

			}

			max += i;

			pci_fixup_parent_subordinate_busnr(child, max);

		}
@@ -561,6 +580,22 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max 


	sprintf(child->name, (is_cardbus ? "PCI CardBus #%02x" : "PCI Bus #%02x"), child->number);



	while (bus->parent) {

		if ((child->subordinate > bus->subordinate) ||

		    (child->number > bus->subordinate) ||

		    (child->number < bus->number) ||

		    (child->subordinate < bus->number)) {

			printk(KERN_WARNING "PCI: Bus #%02x (-#%02x) may be "

			       "hidden behind%s bridge #%02x (-#%02x)%s\n",

			       child->number, child->subordinate,

			       bus->self->transparent ? " transparent" : " ",

			       bus->number, bus->subordinate,

			       pcibios_assign_all_busses() ? " " :

			       " (try 'pci=assign-busses')");

		}

		bus = bus->parent;

	}



	return max;

}