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feat(Power_Management): Add LPM failure debugging guide for AM62L
Add detailed documentation for debugging low power mode failures on AM62LX platform. The guide provides step-by-step instructions for enabling SYSFW trace logs and troubleshooting suspend/resume issues. Signed-off-by: Akashdeep Kaur <[email protected]>
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‎configs/AM62LX/AM62LX_linux_toc.txt‎

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@@ -77,6 +77,7 @@ linux/Foundational_Components/Power_Management/pm_overview
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linux/Foundational_Components/Power_Management/pm_cpuidle
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linux/Foundational_Components/Power_Management/pm_am62lx_low_power_modes
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linux/Foundational_Components/Power_Management/pm_wakeup_sources
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linux/Foundational_Components/Power_Management/pm_am62lx_debug
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linux/Foundational_Components/System_Security/Security_overview
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#linux/Foundational_Components/System_Security/SELinux

‎source/linux/Foundational_Components/Power_Management/pm_am62lx_debug.rst‎

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.. _pm_debug:
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#################
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Debug Information
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#################
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***************
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Low Power Modes
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***************
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Overview
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========
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Implementing Low Power Modes requires synchronization between multiple
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software components. Debugging a LPM issue requires finding out which
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component (Linux, TF-A or TIFS) might be at fault.
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The comprehensive way of debugging LPM starts by looking at all
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the commands that have been executed by the TIFS and TF-A firmware.
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The TIFS and TF-A firmware will trace the low power mode sequence and dump a series of
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representative hex values. These hex values are not in human-readable form, so the SYSFW Trace
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Parser Script :doc:`/linux/How_to_Guides/Host/SYSFW_Trace_Parser` helps translate the hex values into a readable format.
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These transactions can be found on the WKUP UART port (``/dev/ttyUSB2``).
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Prerequisites
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=============
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Before using the parser, the following steps are required to enable the SYSFW trace to include
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Low Power Mode sequencing:
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1. Enable low power logs in the board configuration file
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2. Remove isolation from I/Os and enable appropriate log level in TF-A
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Step 1: Enable Low Power Logs in Board Configuration
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=====================================================
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Apply the following patch in the U-Boot source code to enable trace logs.
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File location:
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.. code-block:: text
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<SDK Install Directory>/board-support/ti-u-boot-<version>/board/ti/am62lx/board-cfg.yaml
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Patch to apply:
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.. code-block:: diff
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diff --git a/board/ti/am62lx/board-cfg.yaml b/board/ti/am62lx/board-cfg.yaml
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index a0297c284a6..a535a73734d 100644
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--- a/board/ti/am62lx/board-cfg.yaml
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+++ b/board/ti/am62lx/board-cfg.yaml
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@@ -28,5 +28,5 @@ board-cfg:
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subhdr:
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magic: 0x020C
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size: 8
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- trace_dst_enables: 0x00
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- trace_src_enables: 0x00
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+ trace_dst_enables: 0x0D
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+ trace_src_enables: 0x7F
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After applying the patch, re-build U-Boot following the instructions in :ref:`u-boot-build-guide-build-k3`.
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Make sure to copy the target images to your boot media.
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Step 2: Remove I/O Isolation and Enable Logging in TF-A
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========================================================
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Apply the following patch in the TF-A (Arm Trusted Firmware) source code to disable I/O isolation
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and enable debug logging.
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File location:
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.. code-block:: text
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<SDK Install Directory>/board-support/arm-trusted-firmware-<version>/plat/ti/k3/common/am62l_psci.c
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Patch to apply:
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.. code-block:: diff
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diff --git a/plat/ti/k3/common/am62l_psci.c b/plat/ti/k3/common/am62l_psci.c
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index 3df4986e5..bd20c8413 100644
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--- a/plat/ti/k3/common/am62l_psci.c
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+++ b/plat/ti/k3/common/am62l_psci.c
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@@ -329,7 +329,7 @@ static void am62l_pwr_domain_suspend(const psci_power_state_t *target_state)
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if ((mode == 0) || (mode == 6)) {
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INFO("Started Suspend Sequence in ATF\n");
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/* Isolate the I/Os to allow I/O Daisy chain wakeup */
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- k3_lpm_set_io_isolation(true);
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+ // k3_lpm_set_io_isolation(true);
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k3_lpm_config_magic_words(mode);
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ti_sci_prepare_sleep(mode, context_save_addr, 0);
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INFO("sent prepare message\n");
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.. important::
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Modifying the I/O isolation code will impact the functionality of any wake-up source that uses
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I/O Daisy Chain, such as Main Domain UART. Refer to the `TRM <https://www.ti.com/lit/ug/sprujb4a/sprujb4a.pdf>`__
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section 6.2.3.11 I/O Power Management and Daisy Chaining for more information.
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After applying the patch, re-compile TF-A with ``LOG_LEVEL=20`` (LOG_LEVEL_INFO). Follow the
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instructions in :ref:`foundational-components-atf` for building TF-A.
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Make sure to copy the new ``bl31.bin`` image to your boot media.
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Generating Logs & Running the Parser Script
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============================================
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Boot the device with the new changes made. To isolate the low power mode related logs, start
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running the parser script right before entering low power mode.
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Step 1: Prepare the EVM Terminal
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---------------------------------
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On the EVM terminal, get it ready to enter low power mode:
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.. code-block:: console
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root@am62lxx-evm:~# echo mem > /sys/power/state
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Step 2: Setup the Parser Script on Host
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----------------------------------------
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On the Host terminal, setup the script:
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.. code-block:: console
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HOST:~$ cd <SDK Install Directory>/bin
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HOST:~$ python3 sysfw_trace_parser.py -d /dev/ttyUSB2 -o <output file> -Tv <version>
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For example, using version ``0x03007``:
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.. code-block:: console
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HOST:~$ python3 sysfw_trace_parser.py -d /dev/ttyUSB2 -o am62lx_lpm_trace.txt -Tv 0x03007
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Step 3: Execute and Capture Logs
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---------------------------------
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Once both terminals are ready:
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1. Run the Parser Script on the host terminal
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2. Execute the low power command on the EVM terminal
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3. Send a keyboard interrupt (``Ctrl + C``) to the parser script once the device wakes up
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The human-readable logs will be saved in the designated output file.
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Alternative: Direct Terminal Output
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------------------------------------
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Alternatively, the parser script can write the log output directly to the terminal instead of
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a file:
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.. code-block:: console
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HOST:~$ python3 sysfw_trace_parser.py -d /dev/ttyUSB2 -O -Tv 0x03007
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Troubleshooting: Parser Errors
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===============================
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Sometimes the parser results in an error:
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.. code-block:: text
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invalid literal for int() with base 16: '0x6C001700H0x6C001820'
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**Workaround:** Copy the logs directly from ``/dev/ttyUSB2`` and save it as an input file.
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The error is caused by the hex values not creating a new line.
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When using the workaround with a saved log file, run the parser script as follows:
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.. code-block:: console
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HOST:~$ python3 sysfw_trace_parser.py -l <input hex log file> -o <output file> -Tv 0x03007
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Or for direct terminal output:
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.. code-block:: console
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HOST:~$ python3 sysfw_trace_parser.py -l <input hex log file> -O -Tv 0x03007
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Interpreting the Logs
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======================
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The generated logs contain detailed information about the low power mode sequence execution.
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.. note::
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For detailed information on interpreting the logs, refer to the `low power mode sequence documentation <https://software-dl.ti.com/tisci/esd/latest/4_trace/trace.html#low-power-mode-sequence-id>`__.
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The logs will show:
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- Security management action IDs and their status
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- Sequence of operations during suspend and resume
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- Any errors or warnings during the low power mode transition
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Additional information: Decoding Drivers Failure during suspend
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===============================================================
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Sometimes the suspend does not go through. In that case, the console suspend can be delayed to get the logs at
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low power mode suspend time using the below command:
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.. code-block:: console
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root@am62lxx-evm:~# echo N | sudo tee /sys/module/printk/parameters/console_suspend
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root@am62lxx-evm:~# echo mem > /sys/power/state
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This can be used to debug whether any drivers in linux failed to enter suspend.

‎source/linux/Foundational_Components_Power_Management.rst‎

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Foundational_Components/Power_Management/pm_wakeup_sources
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Foundational_Components/Power_Management/pm_sw_arch
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Foundational_Components/Power_Management/pm_debug
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Foundational_Components/Power_Management/pm_am62lx_debug

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