1.. SPDX-License-Identifier: GPL-2.0 2 3=========================== 4Subsystem Trace Points: PCI 5=========================== 6 7Overview 8======== 9The PCI tracing system provides tracepoints to monitor critical hardware events 10that can impact system performance and reliability. These events normally show 11up here: 12 13 /sys/kernel/tracing/events/pci 14 15Cf. include/trace/events/pci.h for the events definitions. 16 17Available Tracepoints 18===================== 19 20pci_hp_event 21------------ 22 23Monitors PCI hotplug events including card insertion/removal and link 24state changes. 25:: 26 27 pci_hp_event "%s slot:%s, event:%s\n" 28 29**Event Types**: 30 31* ``LINK_UP`` - PCIe link established 32* ``LINK_DOWN`` - PCIe link lost 33* ``CARD_PRESENT`` - Card detected in slot 34* ``CARD_NOT_PRESENT`` - Card removed from slot 35 36**Example Usage**:: 37 38 # Enable the tracepoint 39 echo 1 > /sys/kernel/debug/tracing/events/pci/pci_hp_event/enable 40 41 # Monitor events (the following output is generated when a device is hotplugged) 42 cat /sys/kernel/debug/tracing/trace_pipe 43 irq/51-pciehp-88 [001] ..... 1311.177459: pci_hp_event: 0000:00:02.0 slot:10, event:CARD_PRESENT 44 45 irq/51-pciehp-88 [001] ..... 1311.177566: pci_hp_event: 0000:00:02.0 slot:10, event:LINK_UP 46 47pcie_link_event 48--------------- 49 50Monitors PCIe link speed changes and provides detailed link status information. 51:: 52 53 pcie_link_event "%s type:%d, reason:%d, cur_bus_speed:%d, max_bus_speed:%d, width:%u, flit_mode:%u, status:%s\n" 54 55**Parameters**: 56 57* ``type`` - PCIe device type (4=Root Port, etc.) 58* ``reason`` - Reason for link change: 59 60 - ``0`` - Link retrain 61 - ``1`` - Bus enumeration 62 - ``2`` - Bandwidth notification enable 63 - ``3`` - Bandwidth notification IRQ 64 - ``4`` - Hotplug event 65 66 67**Example Usage**:: 68 69 # Enable the tracepoint 70 echo 1 > /sys/kernel/debug/tracing/events/pci/pcie_link_event/enable 71 72 # Monitor events (the following output is generated when a device is hotplugged) 73 cat /sys/kernel/debug/tracing/trace_pipe 74 irq/51-pciehp-88 [001] ..... 381.545386: pcie_link_event: 0000:00:02.0 type:4, reason:4, cur_bus_speed:20, max_bus_speed:23, width:1, flit_mode:0, status:DLLLA 75