On Thu, Nov 10, 2011 at 09:00:13AM -0500, Prarit Bhargava wrote:
> Stratus systems have a hierarchy that includes a PCIE Downstream bridge
> connected to a PCIE Upstream bridge and a PCI Downstream bridge. The system
> boots with this wrong hierarchy into a crippled mode (USB doesn't work,
> network doesn't work ...). Avoiding the Downstream bridge check in
> only_one_child() causes all the bridges to be enumerated and the system
> to function properly.
> @@ -1275,7 +1276,15 @@ static int only_one_child(struct pci_bus *bus)
> struct pci_dev *parent = bus->self;
> if (!parent || !pci_is_pcie(parent))
> return 0;
> - if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
> + if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT)
> + return 1;
> + /*
> + * Stratus/NEC ftServer systems have a broken PCIE hierarchy in which
> + * one upstream and one downstream port are plugged into a downstream
> + * port. Avoiding the downstream port check here results in a
> + * functional system.
> + */
> + if (!dmi_name_in_vendors("ftServer") &&
> parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM)
> return 1;
> return 0;
dmi_name_in_vendors is relatively expensive, so the order of these two
should be swapped, at least:
> if (parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM &&
> !dmi_name_in_vendors("ftServer"))
Plus, this gets called for every PCI bridge. We should be caching it
somewhere, so it's only called once.
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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