5.4-stable review patch. If anyone has any objections, please let me know.
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From: Feng Tang feng.tang@linux.alibaba.com
[ Upstream commit 9d7db4db19827380e225914618c0c1bf435ed2f5 ]
Firmware developers reported that Linux issues two PCIe hotplug commands in very short intervals on an ARM server, which doesn't comply with the PCIe spec. According to PCIe r6.1, sec 6.7.3.2, if the Command Completed event is supported, software must wait for a command to complete or wait at least 1 second before sending a new command.
In the failure case, the first PCIe hotplug command is from get_port_device_capability(), which sends a command to disable PCIe hotplug interrupts without waiting for its completion, and the second command comes from pcie_enable_notification() of pciehp driver, which enables hotplug interrupts again.
Fix this by only disabling the hotplug interrupts when the pciehp driver is not enabled.
Link: https://lore.kernel.org/r/20250303023630.78397-1-feng.tang@linux.alibaba.com Fixes: 2bd50dd800b5 ("PCI: PCIe: Disable PCIe port services during port initialization") Suggested-by: Lukas Wunner lukas@wunner.de Signed-off-by: Feng Tang feng.tang@linux.alibaba.com [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Lukas Wunner lukas@wunner.de Reviewed-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/pcie/portdrv_core.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c index 8637f6068f9c2..07d2699286448 100644 --- a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c @@ -214,10 +214,12 @@ static int get_port_device_capability(struct pci_dev *dev)
/* * Disable hot-plug interrupts in case they have been enabled - * by the BIOS and the hot-plug service driver is not loaded. + * by the BIOS and the hot-plug service driver won't be loaded + * to handle them. */ - pcie_capability_clear_word(dev, PCI_EXP_SLTCTL, - PCI_EXP_SLTCTL_CCIE | PCI_EXP_SLTCTL_HPIE); + if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE)) + pcie_capability_clear_word(dev, PCI_EXP_SLTCTL, + PCI_EXP_SLTCTL_CCIE | PCI_EXP_SLTCTL_HPIE); }
#ifdef CONFIG_PCIEAER