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The PCI controller tracepoint, pcie_ltssm_state_transition, monitors the LTSSM state transition and data rate changes for debugging purposes. Add documentation for it. Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> [mani: added MAINTAINERS entry] Signed-off-by: Manivannan Sadhasivam <mani@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Link: https://patch.msgid.link/1774403912-210670-3-git-send-email-shawn.lin@rock-chips.com
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1.2 KiB
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43 lines
1.2 KiB
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.. SPDX-License-Identifier: GPL-2.0
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======================================
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Subsystem Trace Points: PCI Controller
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======================================
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Overview
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========
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The PCI controller tracing system provides tracepoints to monitor controller
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level information for debugging purpose. The events normally show up here:
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/sys/kernel/tracing/events/pci_controller
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Cf. include/trace/events/pci_controller.h for the events definitions.
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Available Tracepoints
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=====================
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pcie_ltssm_state_transition
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---------------------------
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Monitors PCIe LTSSM state transition including state and rate information
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::
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pcie_ltssm_state_transition "dev: %s state: %s rate: %s\n"
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**Parameters**:
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* ``dev`` - PCIe controller instance
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* ``state`` - PCIe LTSSM state
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* ``rate`` - PCIe date rate
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**Example Usage**:
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.. code-block:: shell
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# Enable the tracepoint
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echo 1 > /sys/kernel/debug/tracing/events/pci_controller/pcie_ltssm_state_transition/enable
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# Monitor events (the following output is generated when a device is linking)
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cat /sys/kernel/debug/tracing/trace_pipe
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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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