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PCI: Get rid of dev->has_secondary_link flag

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In some systems, the Device/Port Type in the PCI Express Capabilities
register incorrectly identifies upstream ports as downstream ports.

d0751b98df ("PCI: Add dev->has_secondary_link to track downstream PCIe
links") addressed this by adding pci_dev.has_secondary_link, which is set
for downstream ports.  But this is confusing because pci_pcie_type()
sometimes gives the wrong answer, and it's not obvious that we should use
pci_dev.has_secondary_link instead.

Reduce the confusion by correcting the type of the port itself so that
pci_pcie_type() returns the actual type regardless of what the Device/Port
Type register claims it is.  Update the users to call pci_pcie_type() and
pcie_downstream_port() accordingly, and remove pci_dev.has_secondary_link
completely.

Link: https://lore.kernel.org/linux-pci/20190703133953.GK128603@google.com/
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20190822085553.62697-2-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Mika Westerberg
2019-08-22 11:55:53 +03:00
committed by Bjorn Helgaas
parent 984998e340
commit ca78410403
6 changed files with 37 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
drivers/pci/probe.c
View File

@@ -1431,26 +1431,38 @@ void set_pcie_port_type(struct pci_dev *pdev)
pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, &reg16);
pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;
parent = pci_upstream_bridge(pdev);
if (!parent)
return;
/*
* A Root Port or a PCI-to-PCIe bridge is always the upstream end
* of a Link. No PCIe component has two Links. Two Links are
* connected by a Switch that has a Port on each Link and internal
* logic to connect the two Ports.
* Some systems do not identify their upstream/downstream ports
* correctly so detect impossible configurations here and correct
* the port type accordingly.
*/
type = pci_pcie_type(pdev);
if (type == PCI_EXP_TYPE_ROOT_PORT ||
type == PCI_EXP_TYPE_PCIE_BRIDGE)
pdev->has_secondary_link = 1;
else if (type == PCI_EXP_TYPE_UPSTREAM ||
type == PCI_EXP_TYPE_DOWNSTREAM) {
parent = pci_upstream_bridge(pdev);
if (type == PCI_EXP_TYPE_DOWNSTREAM) {
/*
* Usually there's an upstream device (Root Port or Switch
* Downstream Port), but we can't assume one exists.
* If pdev claims to be downstream port but the parent
* device is also downstream port assume pdev is actually
* upstream port.
*/
if (parent && !parent->has_secondary_link)
pdev->has_secondary_link = 1;
if (pcie_downstream_port(parent)) {
pci_info(pdev, "claims to be downstream port but is acting as upstream port, correcting type\n");
pdev->pcie_flags_reg &= ~PCI_EXP_FLAGS_TYPE;
pdev->pcie_flags_reg |= PCI_EXP_TYPE_UPSTREAM;
}
} else if (type == PCI_EXP_TYPE_UPSTREAM) {
/*
* If pdev claims to be upstream port but the parent
* device is also upstream port assume pdev is actually
* downstream port.
*/
if (pci_pcie_type(parent) == PCI_EXP_TYPE_UPSTREAM) {
pci_info(pdev, "claims to be upstream port but is acting as downstream port, correcting type\n");
pdev->pcie_flags_reg &= ~PCI_EXP_FLAGS_TYPE;
pdev->pcie_flags_reg |= PCI_EXP_TYPE_DOWNSTREAM;
}
}
}
@@ -2488,12 +2500,8 @@ static int only_one_child(struct pci_bus *bus)
* A PCIe Downstream Port normally leads to a Link with only Device
* 0 on it (PCIe spec r3.1, sec 7.3.1). As an optimization, scan
* only for Device 0 in that situation.
*
* Checking has_secondary_link is a hack to identify Downstream
* Ports because sometimes Switches are configured such that the
* PCIe Port Type labels are backwards.
*/
if (bridge && pci_is_pcie(bridge) && bridge->has_secondary_link)
if (bridge && pci_is_pcie(bridge) && pcie_downstream_port(bridge))
return 1;
return 0;