Hello,
I'm running u-boot-1.0.0 on a IBM PPC440GP. I have a custom made board with 2 pci-to-pci bridge Intel 21154BE and several devices behind it. (* PCI bus layout) On boot-up, u-boot immediately recognizes the 2 bridges and 1 device on bus 0. It also has no problem for enumirating all the devices on bus 1, but u-boot can't find any device on bus 2. When I look at the bridge configuration using the 'pci 0 long' command, I see that the secondary bus address field of bridge 1 is set to 1. This should be 2. I also see that on bridge 1 but also on bridge 0 the subordinate bus address field always is filled with a 0.
First of all I already implemented the type1 configuration cycle bug fix at (..\drivers\Pci_indirect.c).
To work this kind of PCI configuration, I changed the following lines: 1. The problem with the secondary bus address is fixed by changing pci_hose_write_config_byte(hose, dev, PCI_SECONDARY_BUS, sub_bus + 1); to pci_hose_write_config_byte(hose, dev, PCI_SECONDARY_BUS, hose->current_busno); in (file: '..\drivers\Pci_auto.c'; function: 'static void pciauto_prescan_setup_bridge()) 2. The problem with the subordinate bus address is solved by swapping the code lines from pciauto_postscan_setup_bridge(hose, dev, sub_bus); sub_bus = hose->current_busno; to sub_bus = hose->current_busno; pciauto_postscan_setup_bridge(hose, dev, sub_bus); (file: '..\drivers\Pci_auto.c'; function: int pciauto_config_device())
I'm not sure if this fix is fully failed proof but it works fine for this design.
I hope my findings can be a contribution to the u-boot project.
* PCI bus layout.
BUS0 | | | /-------\ BUS1 |---| |-------- -> 7 PCI devices | -------/ | Bridge 0 | | | /-------\ BUS2 |---| |-------- -> 7 PCI devices | -------/ | Bridge 1 | | |--- 1 PCI device
Greetings, Philippe