From 4d357e4209c14ab340b0b9b64798099937b5922e Mon Sep 17 00:00:00 2001 From: Alexandru Gagniuc Date: Mon, 27 Jul 2020 11:11:31 -0400 Subject: [PATCH] PCI: pciehp: Wait for PDS if in-band presence is disabled task #29600094 commit f496648b99f8f7f6711f7c30a6327381f37dd1e8 upstream. Backport summary: for 4.19 kernel ICX PCIe Gen4 support. When in-band presence detect is disabled, PDS may come up at any time or not at all. PDS being low may indicate that the card is still mating, and we could expect contact bounce to bring down the link as well. It is reasonable to assume that most cards will mate in a hotplug slot in about a second. Thus, when we know PDS only reflects out-of-band presence detect, it's worthwhile to wait the extra second or so to make sure the card is properly mated before loading the driver and to prevent the hotplug code from disabling a device if the presence detect change goes active after the device is enabled. Link: https://lore.kernel.org/r/20191025190047.38130-3-stuart.w.hayes@gmail.com [bhelgaas: use ctrl_info() instead of pci_info()] Signed-off-by: Alexandru Gagniuc Signed-off-by: Stuart Hayes Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Lukas Wunner (cherry picked from commit f496648b99f8f7f6711f7c30a6327381f37dd1e8) Signed-off-by: Ethan Zhao Signed-off-by: Artie Ding Acked-by: Caspar Zhang --- drivers/pci/hotplug/pciehp_hpc.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index ba93084f510a..278c87fa9a6b 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -243,6 +243,22 @@ static bool pci_bus_check_dev(struct pci_bus *bus, int devfn) return found; } +static void pcie_wait_for_presence(struct pci_dev *pdev) +{ + int timeout = 1250; + u16 slot_status; + + do { + pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); + if (slot_status & PCI_EXP_SLTSTA_PDS) + return; + msleep(10); + timeout -= 10; + } while (timeout > 0); + + pci_info(pdev, "Timeout waiting for Presence Detect\n"); +} + int pciehp_check_link_status(struct controller *ctrl) { struct pci_dev *pdev = ctrl_dev(ctrl); @@ -252,6 +268,9 @@ int pciehp_check_link_status(struct controller *ctrl) if (!pcie_wait_for_link(pdev, true)) return -1; + if (ctrl->inband_presence_disabled) + pcie_wait_for_presence(pdev); + found = pci_bus_check_dev(ctrl->pcie->port->subordinate, PCI_DEVFN(0, 0)); -- GitLab