Revert "PCI: Don't scan random busses in pci_scan_bridge()"
This reverts commitfc1b253141
("PCI: Don't scan random busses in pci_scan_bridge()") because it breaks CardBus on some machines. David tested a Dell Latitude D505 that worked like this prior tofc1b253141
: pci 0000:00:1e.0: PCI bridge to [bus 01] pci 0000:01:01.0: CardBus bridge to [bus 02-05] Note that the 01:01.0 CardBus bridge has a bus number aperture of [bus 02-05], but those buses are all outside the 00:1e.0 PCI bridge bus number aperture, so accesses to buses 02-05 never reach CardBus. This is later patched up by yenta_fixup_parent_bridge(), which changes the subordinate bus number of the 00:1e.0 PCI bridge: pci_bus 0000:01: Raising subordinate bus# of parent bus (#01) from #01 to #05 Withfc1b253141
, pci_scan_bridge() fails immediately when it notices that we can't allocate a valid secondary bus number for the CardBus bridge, and CardBus doesn't work at all: pci 0000:01:01.0: can't allocate child bus 01 from [bus 01] I'd prefer to fix this by integrating the yenta_fixup_parent_bridge() logic into pci_scan_bridge() so we fix the bus number apertures up front. But I don't think we can do that before v3.17, so I'm going to revert this to avoid the problem while we're working on the long-term fix. Link: https://bugzilla.kernel.org/show_bug.cgi?id=83441 Link: http://lkml.kernel.org/r/1409303414-5196-1-git-send-email-david.henningsson@canonical.com Reported-by: David Henningsson <david.henningsson@canonical.com> Tested-by: David Henningsson <david.henningsson@canonical.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> CC: stable@vger.kernel.org # v3.15+
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@ -838,16 +838,12 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
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goto out;
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}
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if (max >= bus->busn_res.end) {
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dev_warn(&dev->dev, "can't allocate child bus %02x from %pR\n",
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max, &bus->busn_res);
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goto out;
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}
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/* Clear errors */
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pci_write_config_word(dev, PCI_STATUS, 0xffff);
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/* The bus will already exist if we are rescanning */
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/* Prevent assigning a bus number that already exists.
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* This can happen when a bridge is hot-plugged, so in
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* this case we only re-scan this bus. */
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child = pci_find_bus(pci_domain_nr(bus), max+1);
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if (!child) {
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child = pci_add_new_bus(bus, dev, max+1);
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