Some (defective) PCIe devices are not able to reliably do link retraining.
Check to see if ASPM is possible between link partners before configuring
common clocking, and doing the resulting link retraining. If ASPM is not
possible, there is no reason to risk losing access to a device due to an
unnecessary link retraining.
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
+ /* Get upstream/downstream components' register state */
+ pcie_get_aspm_reg(parent, &upreg);
+ child = list_entry(linkbus->devices.next, struct pci_dev, bus_list);
+ pcie_get_aspm_reg(child, &dwreg);
+
+ /*
+ * If ASPM not supported, don't mess with the clocks and link,
+ * bail out now.
+ */
+ if (!(upreg.support & dwreg.support))
+ return;
+
/* Configure common clock before checking latencies */
pcie_aspm_configure_common_clock(link);
/* Configure common clock before checking latencies */
pcie_aspm_configure_common_clock(link);
- /* Get upstream/downstream components' register state */
+ /*
+ * Re-read upstream/downstream components' register state
+ * after clock configuration
+ */
pcie_get_aspm_reg(parent, &upreg);
pcie_get_aspm_reg(parent, &upreg);
- child = list_entry(linkbus->devices.next, struct pci_dev, bus_list);
pcie_get_aspm_reg(child, &dwreg);
/*
pcie_get_aspm_reg(child, &dwreg);
/*