From 12d8706963f073fffad16c7c24160ef20d9aeaff Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Fri, 19 Sep 2014 11:08:40 -0600 Subject: [PATCH] Revert "PCI: Make sure bus number resources stay within their parents bounds" This reverts commit 1820ffdccb9b ("PCI: Make sure bus number resources stay within their parents bounds") because it breaks some systems with LSI Logic FC949ES Fibre Channel Adapters, apparently by exposing a defect in those adapters. Dirk tested a Tyan VX50 (B4985) with this device that worked like this prior to 1820ffdccb9b: bus: [bus 00-7f] on node 0 link 1 ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-07]) pci 0000:00:0e.0: PCI bridge to [bus 0a] pci_bus 0000:0a: busn_res: can not insert [bus 0a] under [bus 00-07] (conflicts with (null) [bus 00-07]) pci 0000:0a:00.0: [1000:0646] type 00 class 0x0c0400 (FC adapter) Note that the root bridge [bus 00-07] aperture is wrong; this is a BIOS defect in the PCI0 _CRS method. But prior to 1820ffdccb9b, we didn't enforce that aperture, and the FC adapter worked fine at 0a:00.0. After 1820ffdccb9b, we notice that 00:0e.0's aperture is not contained in the root bridge's aperture, so we reconfigure it so it *is* contained: pci 0000:00:0e.0: bridge configuration invalid ([bus 0a-0a]), reconfiguring pci 0000:00:0e.0: PCI bridge to [bus 06-07] This effectively moves the FC device from 0a:00.0 to 07:00.0, which should be legal. But when we enumerate bus 06, the FC device doesn't respond, so we don't find anything. This is probably a defect in the FC device. Possible fixes (due to Yinghai): 1) Add a quirk to fix the _CRS information based on what amd_bus.c read from the hardware 2) Reset the FC device after we change its bus number 3) Revert 1820ffdccb9b Fix 1 would be relatively easy, but it does sweep the LSI FC issue under the rug. We might want to reconfigure bus numbers in the future for some other reason, e.g., hotplug, and then we could trip over this again. For that reason, I like fix 2, but we don't know whether it actually works, and we don't have a patch for it yet. This revert is fix 3, which also sweeps the LSI FC issue under the rug. Link: https://bugzilla.kernel.org/show_bug.cgi?id=84281 Reported-by: Dirk Gouders Tested-by: Dirk Gouders Signed-off-by: Bjorn Helgaas CC: stable@vger.kernel.org # v3.15+ CC: Yinghai Lu --- drivers/pci/probe.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 7c8ca351beae..4170113cde61 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -775,7 +775,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass) /* Check if setup is sensible at all */ if (!pass && (primary != bus->number || secondary <= bus->number || - secondary > subordinate || subordinate > bus->busn_res.end)) { + secondary > subordinate)) { dev_info(&dev->dev, "bridge configuration invalid ([bus %02x-%02x]), reconfiguring\n", secondary, subordinate); broken = 1; @@ -849,8 +849,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass) child = pci_add_new_bus(bus, dev, max+1); if (!child) goto out; - pci_bus_insert_busn_res(child, max+1, - bus->busn_res.end); + pci_bus_insert_busn_res(child, max+1, 0xff); } max++; buses = (buses & 0xff000000) @@ -909,11 +908,6 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass) /* * Set the subordinate bus number to its real value. */ - if (max > bus->busn_res.end) { - dev_warn(&dev->dev, "max busn %02x is outside %pR\n", - max, &bus->busn_res); - max = bus->busn_res.end; - } pci_bus_update_busn_res_end(child, max); pci_write_config_byte(dev, PCI_SUBORDINATE_BUS, max); } -- 2.39.5