diff options
Diffstat (limited to 'drivers/pci/pci.c')
| -rw-r--r-- | drivers/pci/pci.c | 128 |
1 files changed, 122 insertions, 6 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 11e4b495cfac..b9d91370856a 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1021,14 +1021,11 @@ int pci_power_up(struct pci_dev *dev) pci_platform_power_transition(dev, PCI_D0); /* - * Mandatory power management transition delays, see PCI Express Base - * Specification Revision 2.0 Section 6.6.1: Conventional Reset. Do not - * delay for devices powered on/off by corresponding bridge, because - * have already delayed for the bridge. + * Mandatory power management transition delays are handled in + * pci_pm_resume_noirq() and pci_pm_runtime_resume() of the + * corresponding bridge. */ if (dev->runtime_d3cold) { - if (dev->d3cold_delay && !dev->imm_ready) - msleep(dev->d3cold_delay); /* * When powering on a bridge from D3cold, the whole hierarchy * may be powered on into D0uninitialized state, resume them to @@ -4652,6 +4649,125 @@ bool pcie_wait_for_link(struct pci_dev *pdev, bool active) return pcie_wait_for_link_delay(pdev, active, 100); } +/* + * Find maximum D3cold delay required by all the devices on the bus. The + * spec says 100 ms, but firmware can lower it and we allow drivers to + * increase it as well. + * + * Called with @pci_bus_sem locked for reading. + */ +static int pci_bus_max_d3cold_delay(const struct pci_bus *bus) +{ + const struct pci_dev *pdev; + int min_delay = 100; + int max_delay = 0; + + list_for_each_entry(pdev, &bus->devices, bus_list) { + if (pdev->d3cold_delay < min_delay) + min_delay = pdev->d3cold_delay; + if (pdev->d3cold_delay > max_delay) + max_delay = pdev->d3cold_delay; + } + + return max(min_delay, max_delay); +} + +/** + * pci_bridge_wait_for_secondary_bus - Wait for secondary bus to be accessible + * @dev: PCI bridge + * + * Handle necessary delays before access to the devices on the secondary + * side of the bridge are permitted after D3cold to D0 transition. + * + * For PCIe this means the delays in PCIe 5.0 section 6.6.1. For + * conventional PCI it means Tpvrh + Trhfa specified in PCI 3.0 section + * 4.3.2. + */ +void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev) +{ + struct pci_dev *child; + int delay; + + if (pci_dev_is_disconnected(dev)) + return; + + if (!pci_is_bridge(dev) || !dev->bridge_d3) + return; + + down_read(&pci_bus_sem); + + /* + * We only deal with devices that are present currently on the bus. + * For any hot-added devices the access delay is handled in pciehp + * board_added(). In case of ACPI hotplug the firmware is expected + * to configure the devices before OS is notified. + */ + if (!dev->subordinate || list_empty(&dev->subordinate->devices)) { + up_read(&pci_bus_sem); + return; + } + + /* Take d3cold_delay requirements into account */ + delay = pci_bus_max_d3cold_delay(dev->subordinate); + if (!delay) { + up_read(&pci_bus_sem); + return; + } + + child = list_first_entry(&dev->subordinate->devices, struct pci_dev, + bus_list); + up_read(&pci_bus_sem); + + /* + * Conventional PCI and PCI-X we need to wait Tpvrh + Trhfa before + * accessing the device after reset (that is 1000 ms + 100 ms). In + * practice this should not be needed because we don't do power + * management for them (see pci_bridge_d3_possible()). + */ + if (!pci_is_pcie(dev)) { + pci_dbg(dev, "waiting %d ms for secondary bus\n", 1000 + delay); + msleep(1000 + delay); + return; + } + + /* + * For PCIe downstream and root ports that do not support speeds + * greater than 5 GT/s need to wait minimum 100 ms. For higher + * speeds (gen3) we need to wait first for the data link layer to + * become active. + * + * However, 100 ms is the minimum and the PCIe spec says the + * software must allow at least 1s before it can determine that the + * device that did not respond is a broken device. There is + * evidence that 100 ms is not always enough, for example certain + * Titan Ridge xHCI controller does not always respond to + * configuration requests if we only wait for 100 ms (see + * https://bugzilla.kernel.org/show_bug.cgi?id=203885). + * + * Therefore we wait for 100 ms and check for the device presence. + * If it is still not present give it an additional 100 ms. + */ + if (!pcie_downstream_port(dev)) + return; + + if (pcie_get_speed_cap(dev) <= PCIE_SPEED_5_0GT) { + pci_dbg(dev, "waiting %d ms for downstream link\n", delay); + msleep(delay); + } else { + pci_dbg(dev, "waiting %d ms for downstream link, after activation\n", + delay); + if (!pcie_wait_for_link_delay(dev, true, delay)) { + /* Did not train, no need to wait any further */ + return; + } + } + + if (!pci_device_is_present(child)) { + pci_dbg(child, "waiting additional %d ms to become accessible\n", delay); + msleep(delay); + } +} + void pci_reset_secondary_bus(struct pci_dev *dev) { u16 ctrl; |