Prarit,
FYI, this patch does the trick on Draco. I'll try it in the
Stratus lab as well, but I'm 99.99% sure that it will work there
too.
There was one concern when we had a meeting at Stratus to talk
about this: we're not sure if the NEC-branded systems have the
same DMI string or not... I'm trying to find out.
--jim
----- Original Message -----
> Trying [v2]....
>
>
> pci: Workaround Stratus broken PCIE hierarchy
>
> 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.
>
> Unfortunately this hardware is currently available so we should at
> least
> keep it functional.
>
> [v2]
> - ddutile@xxxxxxxxxx requested drivers/pci/quirks.c code
> - matthew@xxxxxxx requested that dmi_name_in_vendors() be called only
> once with a static var check
> - added a kernel parameter to enable scanning of all PCIE devices.
>
> Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
>
> diff --git a/Documentation/kernel-parameters.txt
> b/Documentation/kernel-parameters.txt
> index a0c5c5f..7af458f 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2069,6 +2069,7 @@ bytes respectively. Such letter suffixes can
> also be entirely omitted.
> on: Turn ECRC on.
> realloc reallocate PCI resources if allocations done by BIOS
> are erroneous.
> + pcie_scan_all Scan all possible PCIE devices.
>
> pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State
> Power
> Management.
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 6f45a73..f478bd5 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3589,6 +3589,9 @@ static int __init pci_setup(char *str)
> pcie_bus_config = PCIE_BUS_PERFORMANCE;
> } else if (!strncmp(str, "pcie_bus_peer2peer", 18)) {
> pcie_bus_config = PCIE_BUS_PEER2PEER;
> + } else if (!strncmp(str, "pcie_scan_all", 13)) {
> + printk(KERN_ERR HW_ERR "PCIE: Scanning all devices.\n");
> + pcie_scan_all = 1;
> } else {
> printk(KERN_ERR "PCI: Unknown option `%s'\n",
> str);
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index b74084e..5a07895 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -309,11 +309,16 @@ struct pci_dev_reset_methods {
>
> #ifdef CONFIG_PCI_QUIRKS
> extern int pci_dev_specific_reset(struct pci_dev *dev, int probe);
> +extern int is_broken_pcie_port(void);
> #else
> static inline int pci_dev_specific_reset(struct pci_dev *dev, int
> probe)
> {
> return -ENOTTY;
> }
> +static inline int is_broken_pcie_port(void)
> +{
> + return 0;
> +}
> #endif
>
> #endif /* DRIVERS_PCI_H */
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 04e74f4..fc88a9b 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1270,13 +1270,18 @@ static unsigned no_next_fn(struct pci_dev
> *dev, unsigned fn)
> return 0;
> }
>
> +int pcie_scan_all = 0; /* set via pci=pcie_scan_all */
> static int only_one_child(struct pci_bus *bus)
> {
> struct pci_dev *parent = bus->self;
> + if (pcie_scan_all)
> + return 0;
> if (!parent || !pci_is_pcie(parent))
> return 0;
> - if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
> - parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM)
> + if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT)
> + return 1;
> + if (parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM &&
> + !is_broken_pcie_port())
> return 1;
> return 0;
> }
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 7285145..ef4d0e7 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3092,3 +3092,21 @@ int pci_dev_specific_reset(struct pci_dev
> *dev, int probe)
>
> return -ENOTTY;
> }
> +
> +static int _is_broken_pcie_port = -1;
> +int is_broken_pcie_port(void)
> +{
> + if (_is_broken_pcie_port >= 0)
> + return _is_broken_pcie_port;
> + /*
> + * 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 in only_one_child()
> results
> + * in a functional system.
> + */
> + if (dmi_name_in_vendors("ftServer"))
> + _is_broken_pcie_port = 1;
> + else
> + _is_broken_pcie_port = 0;
> + return _is_broken_pcie_port;
> +}
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 337df0d..745b98e 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1647,5 +1647,7 @@ static inline void
> pci_release_bus_of_node(struct pci_bus *bus) { }
> */
> struct pci_dev *pci_find_upstream_pcie_bridge(struct pci_dev *pdev);
>
> +/* set via pci=pcie_scan_all in order to enumerate all possible PCIE
> busses */
> +extern int pcie_scan_all;
> #endif /* __KERNEL__ */
> #endif /* LINUX_PCI_H */
>
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