On 11/10/2011 09:31 AM, Matthew Wilcox wrote:
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.
Then i recommend a dmi_name_in_vendors() check at init; stick result in
global (or local static), and then it's not exec'd on each bridge, just
a simple flag check.
If that's the case, I'd re-cast my vote for putting the code in pci_quirks
with an export, so it is tracked as a quirk. that may get messy
wrt other arches though (the export in common code; not sure if quirks is
included on all arches).
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