.. SPDX-License-Identifier: GPL-2.0

====================================== Subsystem Trace Points: PCI Controller

Overview

The PCI controller tracing system provides tracepoints to monitor controller level information for debugging purpose. The events normally show up here:

/sys/kernel/tracing/events/pci_controller

Cf. include/trace/events/pci_controller.h for the events definitions.

Available Tracepoints

pcie_ltssm_state_transition

Monitors PCIe LTSSM state transition including state and rate information ::

pcie_ltssm_state_transition  "dev: %s state: %s rate: %s\n"

Parameters:

dev - PCIe controller instance
state - PCIe LTSSM state
rate - PCIe date rate

Example Usage:

.. code-block:: shell

# Enable the tracepoint
echo 1 > /sys/kernel/debug/tracing/events/pci_controller/pcie_ltssm_state_transition/enable

# Monitor events (the following output is generated when a device is linking)
cat /sys/kernel/debug/tracing/trace_pipe
   kworker/0:0-9       [000] .....     5.600221: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_EQ2 rate: 8.0 GT/s