On Thu, May 21, 2015 at 03:05:02PM +0800, Yijing Wang wrote:
> We assumed root port and downstream port always have
> pcie link, downstream port always has a upstream port.
> It's not always correct, In ATCA platform, system has
> unusual pcie topology like:
>
> (root port) (downstream port) (upstream port)
> +-1c.0-[02-0a]----00.0-[03-0a]--+-00.0-[04]--
> | +-01.0-[05]-- (downstream port)
> | +-02.0-[06]--
> | +-03.0-[07]--
> | +-08.0-[08]--
> | +-09.0-[09]--
> | \-0a.0-[0a]--
>
> In this pcie tree, downstream port 02:00.0 has no
> pcie link, and upstream port 03:00.0 has a pcie link.
>
> This patch introduced a new assumption suggested by Bjorn.
> 1. Root port is always on the upstream end of a link.
> 2. The pcie hierarchy should alternate between links
> and internal switch logic, there should be no adjacent
> links or internal buses in pcie tree.
>
> Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
Applied to pci/aspm for v4.2, thanks!
> ---
> drivers/pci/probe.c | 16 ++++++++++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index a9c5e63..192c6b9 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -973,6 +973,7 @@ void set_pcie_port_type(struct pci_dev *pdev)
> {
> int pos;
> u16 reg16;
> + struct pci_dev *parent;
>
> pos = pci_find_capability(pdev, PCI_CAP_ID_EXP);
> if (!pos)
> @@ -982,6 +983,21 @@ void set_pcie_port_type(struct pci_dev *pdev)
> pdev->pcie_flags_reg = reg16;
> pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, ®16);
> pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;
> +
> + /*
> + * We assume root port is always on the upstream end of
> + * a link, and the pcie hierarchy should alternate
> + * between links and internal switch logic.
> + */
> + if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
> + pdev->has_secondary_link = 1;
> +
> + if (pci_pcie_type(pdev) == PCI_EXP_TYPE_UPSTREAM
> + || pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) {
> + parent = pci_upstream_bridge(pdev);
> + if (!parent->has_secondary_link)
> + pdev->has_secondary_link = 1;
> + }
> }
>
> void set_pcie_hotplug_bridge(struct pci_dev *pdev)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 50b7c7d..141fcc1 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -355,6 +355,7 @@ struct pci_dev {
> unsigned int broken_intx_masking:1;
> unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */
> unsigned int irq_managed:1;
> + unsigned int has_secondary_link:1;
> pci_dev_flags_t dev_flags;
> atomic_t enable_cnt; /* pci_enable_device has been called */
>
> --
> 1.7.1
>
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