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feat(Linux): Add AM62L specific LPM documentation
Add docs for AM62LX LPM Signed-off-by: Dhruva Gole <[email protected]>
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‎configs/AM62LX/AM62LX_linux_toc.txt‎

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@@ -66,6 +66,11 @@ linux/Foundational_Components/Kernel/Kernel_Drivers/USB/AM62_DWC3
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linux/Foundational_Components/Kernel/Kernel_Drivers/VTM
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linux/Foundational_Components/Kernel/Kernel_Drivers/Watchdog
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linux/Foundational_Components_Power_Management
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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/System_Security/SELinux
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linux/Foundational_Components_Kernel_Users_Guide

‎source/devices/AM62LX/linux/Release_Specific_Release_Notes.rst‎

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- ATF Based Device Manager including SCMI
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- U-Boot: Legacy Boot Flow, Boot modes (UART, MMCSD, OSPI), CPSW, DMA
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- Kernel: DMA, GPIO, I2C, UART, MMCSD, OSPI NOR, eCAP, eQEP, CPSW, McASP/Audio, DSS, DSI
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- Power Management: Basic Deep Sleep and RTC+DDR mode
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- :ref:`Power Management <am62lx-power-management>`: DeepSleep and RTC+DDR low power modes.
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- RT Kernel : Real-Time Linux Interrupt Latency numbers here - :ref:`RT Interrupt Latencies <RT-linux-performance>`
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- Support for Wifi with M2 CC33xx cards - :ref:`How to Enable M.2-CC33xx in Linux <enable_m2cc3301>`
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- Out-of-Box experience based on LVGL (Light and Versatile Graphics Library) - :ref:`TI LVGL Demo - User Guide <TI-LVGL-Demo-User-Guide-label>`

‎source/linux/Foundational_Components/Power_Management/pm_am62lx_low_power_modes.rst‎

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.. _am62lx-power-management:
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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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.. note::
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For this release, both of the documented low power modes below require special steps which have been
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documented in :ref:`am62l_suspend_workarounds`. This includes the steps to choose the system suspend mode
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and how to wakeup the system.
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The following sections describe a high-level description of the different low power modes (LPM) of the
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device. If your application requires inactive power management, you must determine which
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low power mode described below satisfies your requirements. Each mode must be evaluated
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based on power consumption and latency (the time it takes to wakeup to active mode) requirements. Specific
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values are detailed in the device-specific data sheet. As part of this SDK offering,
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Texas Instruments has added support for the following low power modes (ordered from lowest power consumption
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to highest power consumption):
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#. RTC Only Plus DDR
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#. Deep Sleep
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RTC Only Plus DDR
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*****************
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RTC Only + DDR mode is the deepest low power mode that allows the system to enter a state of lowest power consumption
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while still retaining the DDR RAM context.
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In order to enter RTC Only + DDR mode,
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.. code-block:: console
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root@am62lxx-evm:~# echo mem > /sys/power/state
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[ 67.335138] PM: suspend entry (deep)
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[ 67.358190] Filesystems sync: 0.019 seconds
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[ 67.363206] Freezing user space processes
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[ 67.368991] Freezing user space processes completed (elapsed 0.001 seconds)
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[ 67.376038] OOM killer disabled.
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[ 67.379271] Freezing remaining freezable tasks
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[ 67.384973] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
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[ 67.392398] printk: Suspending console(s) (use no_console_suspend to debug)
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NOTICE: bl1_plat_arch_setup arch setup
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NOTICE: Booting Trusted Firmware
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NOTICE: BL1: v2.12.0(release):11.00.04-7-gaa3963759-dirty
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NOTICE: BL1: Built : 15:56:37, Feb 25 2025
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NOTICE: lpdd4_init <--
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NOTICE: DDR ram size =80000000
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NOTICE: bl1_platform_setup DDR init done
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NOTICE: k3_bl1_handoff sent message to tifs
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ERROR: Wake up src 0x0
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ERROR: Wake up interrupt 0xc
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[ 67.405953] Disabling non-boot CPUs ...
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[ 67.408032] psci: CPU1 killed (polled 0 ms)
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[ 67.408974] Enabling non-boot CPUs ...
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[ 67.409281] Detected VIPT I-cache on CPU1
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[ 67.409330] GICv3: CPU1: found redistributor 1 region 0:0x0000000001860000
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[ 67.409393] CPU1: Booted secondary processor 0x0000000001 [0x410fd034]
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[ 67.410371] CPU1 is up
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[ 67.446329] OOM killer enabled.
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[ 67.449479] Restarting tasks ... done.
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[ 67.454324] random: crng reseeded on system resumption
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[ 67.459689] PM: suspend exit
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DeepSleep
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*********
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DeepSleep AKA Suspend-to-RAM is a low-power mode that allows the SoC
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to retain its state in RAM while the processor is turned off.
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DeepSleep mode is typically used during inactivity when the user requires very low power
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while waiting for an event that requires processing or higher performance. DeepSleep
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is a low power mode which still includes DDR in self-refresh, so wakeup events do not
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require a full cold boot, significantly reducing wakeup latencies.
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Since the power to Always-On power domains are ON throughout DeepSleep,
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power to key modules such as GPIO and others is maintained to allow wakeup events
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to exit out of this mode.
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In order to enter DeepSleep,
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.. code-block:: console
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root@am62lxx-evm:~# echo mem > /sys/power/state
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[ 88.507502] PM: suspend entry (deep)
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[ 88.530523] Filesystems sync: 0.019 seconds
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[ 88.537597] Freezing user space processes
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[ 88.543218] Freezing user space processes completed (elapsed 0.001 seconds)
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[ 88.550275] OOM killer disabled.
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[ 88.553518] Freezing remaining freezable tasks
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[ 88.559139] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
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[ 88.566570] printk: Suspending console(s) (use no_console_suspend to debug)
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ERROR: Wake up src 0x80
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ERROR: Wake up interrupt 0xc
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[ 88.591181] Disabling non-boot CPUs ...
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[ 88.593309] psci: CPU1 killed (polled 0 ms)
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[ 88.594858] Enabling non-boot CPUs ...
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[ 88.595327] Detected VIPT I-cache on CPU1
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[ 88.595379] GICv3: CPU1: found redistributor 1 region 0:0x0000000001860000
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[ 88.595446] CPU1: Booted secondary processor 0x0000000001 [0x410fd034]
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[ 88.596420] CPU1 is up
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[ 88.634778] OOM killer enabled.
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[ 88.637926] Restarting tasks ... done.
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[ 88.642801] random: crng reseeded on system resumption
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[ 88.649913] PM: suspend exit
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root@am62lxx-evm:~#

‎source/linux/Foundational_Components/Power_Management/pm_overview.rst‎

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#. CPUIdle
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#. Runtime PM
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.. ifconfig:: CONFIG_part_variant in ('AM62LX')
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#. Dynamic Frequency Scaling
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#. Runtime PM
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#. CPUIdle
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.. note::
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Dynamic Frequency Scaling and runtime PM are not fully supported on |__PART_FAMILY_DEVICE_NAMES__| as of today,
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and shall be enabled in a future release.
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.. rubric:: Static Power Management
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Static Power Management ensures the SoC is drawing minimum power when
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#. I/O Only Plus DDR
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#. Deep Sleep
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#. MCU Only Mode
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.. ifconfig:: CONFIG_part_variant in ('AM62LX')
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The static power management features on |__PART_FAMILY_DEVICE_NAMES__| are:
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#. RTC Only Plus DDR
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#. Deep Sleep

‎source/linux/Foundational_Components_Power_Management.rst‎

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Foundational_Components/Power_Management/pm_suspend_resume
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Foundational_Components/Power_Management/pm_rtc_ddr
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Foundational_Components/Power_Management/pm_low_power_modes
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Foundational_Components/Power_Management/pm_am62lx_low_power_modes
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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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