1.. SPDX-License-Identifier: GPL-2.0 2 3====================================== 4Subsystem Trace Points: PCI Controller 5====================================== 6 7Overview 8======== 9The PCI controller tracing system provides tracepoints to monitor controller 10level information for debugging purpose. The events normally show up here: 11 12 /sys/kernel/tracing/events/pci_controller 13 14Cf. include/trace/events/pci_controller.h for the events definitions. 15 16Available Tracepoints 17===================== 18 19pcie_ltssm_state_transition 20--------------------------- 21 22Monitors PCIe LTSSM state transition including state and rate information 23:: 24 25 pcie_ltssm_state_transition "dev: %s state: %s rate: %s\n" 26 27**Parameters**: 28 29* ``dev`` - PCIe controller instance 30* ``state`` - PCIe LTSSM state 31* ``rate`` - PCIe date rate 32 33**Example Usage**: 34 35.. code-block:: shell 36 37 # Enable the tracepoint 38 echo 1 > /sys/kernel/debug/tracing/events/pci_controller/pcie_ltssm_state_transition/enable 39 40 # Monitor events (the following output is generated when a device is linking) 41 cat /sys/kernel/debug/tracing/trace_pipe 42 kworker/0:0-9 [000] ..... 5.600221: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_EQ2 rate: 8.0 GT/s 43