[PATCH v5 0/3] PCI Controller event and LTSSM tracepoint support
Manivannan Sadhasivam
mani at kernel.org
Sat Apr 4 09:53:32 PDT 2026
On Wed, Mar 25, 2026 at 09:58:29AM +0800, Shawn Lin wrote:
>
> This patch-set adds new pci controller event and LTSSM tracepoint used by host drivers
> which provide LTSSM trace functionality. The first user is pcie-dw-rockchip with a 256
> Bytes FIFO for recording LTSSM transition.
>
Steve, could you please take a look at the tracing part?
- Mani
> Testing
> =========
>
> This series was tested on RK3588/RK3588s EVB1 with NVMe SSD connected to PCIe3 and PCIe2
> root ports.
>
> echo 1 > /sys/kernel/debug/tracing/events/pci_controller/pcie_ltssm_state_transition/enable
> cat /sys/kernel/debug/tracing/trace_pipe
>
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 64/64 #P:8
> #
> # _-----=> irqs-off/BH-disabled
> # / _----=> need-resched
> # | / _---=> hardirq/softirq
> # || / _--=> preempt-depth
> # ||| / _-=> migrate-disable
> # |||| / delay
> # TASK-PID CPU# ||||| TIMESTAMP FUNCTION
> # | | | ||||| | |
> kworker/0:0-9 [000] ..... 5.600194: pcie_ltssm_state_transition: dev: a40000000.pcie state: DETECT_ACT rate: Unknown
> kworker/0:0-9 [000] ..... 5.600198: pcie_ltssm_state_transition: dev: a40000000.pcie state: DETECT_WAIT rate: Unknown
> kworker/0:0-9 [000] ..... 5.600199: pcie_ltssm_state_transition: dev: a40000000.pcie state: DETECT_ACT rate: Unknown
> kworker/0:0-9 [000] ..... 5.600201: pcie_ltssm_state_transition: dev: a40000000.pcie state: POLL_ACTIVE rate: Unknown
> kworker/0:0-9 [000] ..... 5.600202: pcie_ltssm_state_transition: dev: a40000000.pcie state: POLL_CONFIG rate: Unknown
> kworker/0:0-9 [000] ..... 5.600204: pcie_ltssm_state_transition: dev: a40000000.pcie state: CFG_LINKWD_START rate: Unknown
> kworker/0:0-9 [000] ..... 5.600206: pcie_ltssm_state_transition: dev: a40000000.pcie state: CFG_LINKWD_ACEPT rate: Unknown
> kworker/0:0-9 [000] ..... 5.600207: pcie_ltssm_state_transition: dev: a40000000.pcie state: CFG_LANENUM_WAI rate: Unknown
> kworker/0:0-9 [000] ..... 5.600208: pcie_ltssm_state_transition: dev: a40000000.pcie state: CFG_LANENUM_ACEPT rate: Unknown
> kworker/0:0-9 [000] ..... 5.600210: pcie_ltssm_state_transition: dev: a40000000.pcie state: CFG_COMPLETE rate: Unknown
> kworker/0:0-9 [000] ..... 5.600212: pcie_ltssm_state_transition: dev: a40000000.pcie state: CFG_IDLE rate: Unknown
> kworker/0:0-9 [000] ..... 5.600213: pcie_ltssm_state_transition: dev: a40000000.pcie state: L0 rate: 2.5 GT/s
> kworker/0:0-9 [000] ..... 5.600214: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_LOCK rate: Unknown
> kworker/0:0-9 [000] ..... 5.600216: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_RCVRCFG rate: Unknown
> kworker/0:0-9 [000] ..... 5.600217: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_SPEED rate: Unknown
> kworker/0:0-9 [000] ..... 5.600218: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_LOCK rate: Unknown
> kworker/0:0-9 [000] ..... 5.600220: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_EQ1 rate: Unknown
> kworker/0:0-9 [000] ..... 5.600221: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_EQ2 rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600222: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_EQ3 rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600224: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_LOCK rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600225: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_RCVRCFG rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600226: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_IDLE rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600227: pcie_ltssm_state_transition: dev: a40000000.pcie state: L0 rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600228: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_LOCK rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600229: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_RCVRCFG rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600231: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_IDLE rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600232: pcie_ltssm_state_transition: dev: a40000000.pcie state: L0 rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600233: pcie_ltssm_state_transition: dev: a40000000.pcie state: L123_SEND_EIDLE rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600234: pcie_ltssm_state_transition: dev: a40000000.pcie state: L1_IDLE rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600236: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_LOCK rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600237: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_RCVRCFG rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600238: pcie_ltssm_state_transition: dev: a40000000.pcie state: RCVRY_IDLE rate: 8.0 GT/s
> kworker/0:0-9 [000] ..... 5.600239: pcie_ltssm_state_transition: dev: a40000000.pcie state: L0 rate: 8.0 GT/s
>
>
> Changes in v5:
> - rebase
> - use EM/EMe instead
> - remove reg/unreg function and back to use TRACE_EVENT
> - use trace_pcie_ltssm_state_transition_enabled()
>
> Changes in v4:
> - use TRACE_EVENT_FN to notify when to start and stop the tracepoint,
> and export pci_ltssm_tp_enabled() for host drivers to use
> - skip trace if pci_ltssm_tp_enabled() is false.(Steven)
> - wrap into 80 columns(Bjorn)
>
> Changes in v3:
> - add TRACE_DEFINE_ENUM for all enums(Steven Rostedt)
> - Add toctree entry in Documentation/trace/index.rst(Bagas Sanjaya)
> - fix mismatch section underline length(Bagas Sanjaya)
> - Make example snippets in code block(Bagas Sanjaya)
> - warp context into 80 columns and fix the file name(Bjorn)
> - reorder variables(Mani)
> - rename loop to i; rename en to enable(Mani)
> - use FIELD_GET(Mani)
> - add comment about how the FIFO works(Mani)
>
> Changes in v2:
> - use tracepoint
>
> Shawn Lin (3):
> PCI: trace: Add PCI controller LTSSM transition tracepoint
> Documentation: tracing: Add PCI controller event documentation
> PCI: dw-rockchip: Add pcie_ltssm_state_transition trace support
>
> Documentation/trace/events-pci-controller.rst | 42 ++++++++++
> Documentation/trace/index.rst | 1 +
> drivers/pci/controller/dwc/pcie-dw-rockchip.c | 111 ++++++++++++++++++++++++++
> drivers/pci/trace.c | 1 +
> include/trace/events/pci_controller.h | 58 ++++++++++++++
> 5 files changed, 213 insertions(+)
> create mode 100644 Documentation/trace/events-pci-controller.rst
> create mode 100644 include/trace/events/pci_controller.h
>
> --
> 2.7.4
>
--
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