[PATCH v2 2/3] Documentation: tracing: Add PCI controller event documentation
From: Shawn Lin <shawn.lin@rock-chips.com>
Date: 2026-01-09 03:30:24
Also in:
linux-doc, linux-pci, linux-rockchip
Subsystem:
documentation, the rest, tracing · Maintainers:
Jonathan Corbet, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
The available tracepoint, pcie_ltssm_state_transition, monitors the LTSSM state transistion for debugging purpose. Add description about it. Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> --- Changes in v2: None Documentation/trace/events-pci-conotroller.rst | 41 ++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 Documentation/trace/events-pci-conotroller.rst
diff --git a/Documentation/trace/events-pci-conotroller.rst b/Documentation/trace/events-pci-conotroller.rst
new file mode 100644
index 0000000..8253d00
--- /dev/null
+++ b/Documentation/trace/events-pci-conotroller.rst@@ -0,0 +1,41 @@ +.. 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: +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 root port name +* ``state`` - PCIe LTSSM state +* ``rate`` - PCIe bus speed + +**Example Usage**: + + # Enable the tracepoint + echo 1 > /sys/kernel/debug/tracing/events/pci/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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2.7.4