ChangeSet 1.1119.1.4, 2003/08/08 17:03:19-07:00, ink@jurassic.park.msu.ru [PATCH] PCI: pci_enable_device vs bridges bugs Bug #1 (found by Jay Estabrook). On Alpha, under certain circumstances the firmware may close the IO window of PCI-to-PCI bridge even if there is IO behind. This wouldn't be a problem - linux PCI setup code does set up this window properly, but in addition the firmware clears the IO-enable bit in the PCI_COMMAND register of the bridge. Since we don't call pci_enable_* routines for bridges in non-hotplug path, we end up with disabled IO. Fixed by adding pci_enable_bridges() to pci_assign_unassigned_resources(). Architectures which don't use the latter, but do use other setup-bus code (parisc?) also should call pci_enable_bridges() for each root bus. Bug #2 (closely related to #1). As it turns out, pci_enable_device() doesn't work for bridges at all, only for regular devices (header type 0) due to 0x3f mask passed to pci_enable_device_bars(). The mask should be (1 << PCI_NUM_RESOURCES) - 1. Bug #3 (quite a few archs, including i386). pcibios_enable_device() does only check first 6 resources (regardless of the mask) to decide whether or not to enable IO and MEM. Bridge resources start at 7. #2 and #3 affect hotplug. I wonder, has anybody ever tried *bridged* PCI card behind a hot-plug controller? drivers/pci/pci.c | 2 +- drivers/pci/setup-bus.c | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-) diff -Nru a/drivers/pci/pci.c b/drivers/pci/pci.c --- a/drivers/pci/pci.c Fri Aug 8 17:25:03 2003 +++ b/drivers/pci/pci.c Fri Aug 8 17:25:03 2003 @@ -359,7 +359,7 @@ int pci_enable_device(struct pci_dev *dev) { - return pci_enable_device_bars(dev, 0x3F); + return pci_enable_device_bars(dev, (1 << PCI_NUM_RESOURCES) - 1); } /** diff -Nru a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c --- a/drivers/pci/setup-bus.c Fri Aug 8 17:25:03 2003 +++ b/drivers/pci/setup-bus.c Fri Aug 8 17:25:03 2003 @@ -530,6 +530,8 @@ for(ln=pci_root_buses.next; ln != &pci_root_buses; ln=ln->next) pci_bus_size_bridges(pci_bus_b(ln)); /* Depth last, allocate resources and update the hardware. */ - for(ln=pci_root_buses.next; ln != &pci_root_buses; ln=ln->next) + for(ln=pci_root_buses.next; ln != &pci_root_buses; ln=ln->next) { pci_bus_assign_resources(pci_bus_b(ln)); + pci_enable_bridges(pci_bus_b(ln)); + } }