| Message ID | 20081020230717.2FD16DDDDB@ozlabs.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | a1c19894b786f10c76ac40e93c6b5d70c9b946d2 |
| Headers | show |
On Monday, October 20, 2008 4:06 pm Benjamin Herrenschmidt wrote: > Some firmware fail to properly configure P2P bridges, leaving them > with invalid bus numbers. In some cases, this happens on some embedded > 4xx boards as the result of the kernel allocating different bus space > than the firmware does to host bridges while not setting > pcibios_assign_all_busses() for various reasons. In other cases, it can > just be bogus firmware. > > This adds some sanity checking to the PCI probing code. If a bridge is > found whose primary bus number doesn't match the bus it's sitting on, > or whose secondary bus number not strictly above it's primary bus > number, then the bridge bus numbers are deconfigured in the first pass > of pci_scan_bridge() to be re-assigned in the second pass. > > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > --- > > Ayman, can you double check that this variant of the patch still > fixes your problem ? Thanks ! Sure, seems straightforward enough, I'll wait for Ayman's "Tested-by" before pushing. Thanks, Jesse
Benjamin Herrenschmidt wrote: > > Ayman, can you double check that this variant of the patch still > fixes your problem ? Thanks ! > I've tried it out and it is working correctly with my devices. The subordinate bus numbers on all the ports are correct. Best Regards, Ayman
On Tue, 2008-10-21 at 09:36 -0500, Ayman El-Khashab wrote: > > Ayman, can you double check that this variant of the patch still > > fixes your problem ? Thanks ! > > > > I've tried it out and it is working correctly with my devices. The > subordinate bus numbers on all the ports are correct. Thanks ! Cheers, Ben.
On Tuesday, October 21, 2008 3:33 pm Benjamin Herrenschmidt wrote: > On Tue, 2008-10-21 at 09:36 -0500, Ayman El-Khashab wrote: > > > Ayman, can you double check that this variant of the patch still > > > fixes your problem ? Thanks ! > > > > I've tried it out and it is working correctly with my devices. The > > subordinate bus numbers on all the ports are correct. > > Thanks ! Great, pushed to linux-next. Thanks, Jesse
--- linux-work.orig/drivers/pci/probe.c 2008-10-21 09:47:41.000000000 +1100 +++ linux-work/drivers/pci/probe.c 2008-10-21 09:56:50.000000000 +1100 @@ -480,19 +480,27 @@ int __devinit pci_scan_bridge(struct pci int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS); u32 buses, i, j = 0; u16 bctl; + int broken = 0; pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses); dev_dbg(&dev->dev, "scanning behind bridge, config %06x, pass %d\n", buses & 0xffffff, pass); + /* Check if setup is sensible at all */ + if (!pass && + ((buses & 0xff) != bus->number || ((buses >> 8) & 0xff) <= bus->number)) { + dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n"); + broken = 1; + } + /* Disable MasterAbortMode during probing to avoid reporting of bus errors (in some architectures) */ pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &bctl); pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT); - if ((buses & 0xffff00) && !pcibios_assign_all_busses() && !is_cardbus) { + if ((buses & 0xffff00) && !pcibios_assign_all_busses() && !is_cardbus && !broken) { unsigned int cmax, busnr; /* * Bus already configured by firmware, process it in the first @@ -530,7 +538,7 @@ int __devinit pci_scan_bridge(struct pci * do in the second pass. */ if (!pass) { - if (pcibios_assign_all_busses()) + if (pcibios_assign_all_busses() || broken) /* Temporarily disable forwarding of the configuration cycles on all bridges in this bus segment to avoid possible
Some firmware fail to properly configure P2P bridges, leaving them with invalid bus numbers. In some cases, this happens on some embedded 4xx boards as the result of the kernel allocating different bus space than the firmware does to host bridges while not setting pcibios_assign_all_busses() for various reasons. In other cases, it can just be bogus firmware. This adds some sanity checking to the PCI probing code. If a bridge is found whose primary bus number doesn't match the bus it's sitting on, or whose secondary bus number not strictly above it's primary bus number, then the bridge bus numbers are deconfigured in the first pass of pci_scan_bridge() to be re-assigned in the second pass. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- Ayman, can you double check that this variant of the patch still fixes your problem ? Thanks ! Jesse, if it works for Ayman and you have no objection, can this still go into 2.6.28 ? The root cause of the problem on PPC 4xx is a bit more tricky and will be fixed later but I believe that this added robustness to our code won't harm (and will work around the problem until I have fixed the root cause). drivers/pci/probe.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)