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.. 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
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