From: Alexandru Gagniuc mr.nuke.me@gmail.com
mainline inclusion from mainline-v5.7-rc1 commit f496648b99f8f7f6711f7c30a6327381f37dd1e8 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V CVE: NA
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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 mr.nuke.me@gmail.com Signed-off-by: Stuart Hayes stuart.w.hayes@gmail.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Reviewed-by: Lukas Wunner lukas@wunner.de
(cherry picked from commit f496648b99f8f7f6711f7c30a6327381f37dd1e8) Signed-off-by: Ethan Zhao haifeng.zhao@intel.com Signed-off-by: Jackie Liu liuyun01@kylinos.cn Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Xiongfeng Wang wangxiongfeng2@huawei.com Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- 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 0fff48173247..9d39647a6100 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -238,6 +238,22 @@ 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); @@ -247,6 +263,9 @@ 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));