fix(linux): Update AM62L standby mode documentation by ti-scaria · Pull Request #747 · TexasInstruments/processor-sdk-doc

ti-scaria · 2026-07-17T13:00:53Z

The existing standby mode is renamed from 'low-latency standby' to 'standby' and has been migrated to the default device tree from an overlay. A new 'deep-standby' mode has been added which requires the overlay for use.

Update the docs to reflect these changes, introduce the new deep-standby mode along with its pre-requisites and how to enable the given mode.

akashdeep-ti

Nit: Spelling mistake in commit message

akashdeep-ti · 2026-07-20T05:32:24Z

+
+   The ``cluster_sleep_deep_stby`` state is an optional configuration that can be enabled using the device tree overlay
+   :file:`k3-am62l3-evm-idle-states.dtso`.
+   It provides deeper power savings but requires CPSW and Display drivers to be suspended. Look at section :ref:`deep-standby-mode` for more details.


I think it will be better to add clear note stating that this deeper standby should only be enabled if CPSW and display are to be used in the system.

Also, there is a lot of passive voice usage as vale is reporting, can you correct that?

Acknowledged

akashdeep-ti · 2026-07-20T05:38:32Z

     - Latency

-   * - **cpu_sleep_0** (CPU Level)
+   * - **cpu_sleep_stby** (CPU Level)


I am missing more idle states that you recently added in the DT (to select deep sleep, DSS + DeepSleep, RTC + IO + DDR) etc. Can you please add those as well?

i understand that these idle states are not meant for standby but do we have their documentation elsewhere, then please add it there.

This section I am thinking of keeping for the standby related idle-states only
The s2idle docs will have all the idle-states mentioned

akashdeep-ti · 2026-07-20T10:06:47Z

-   overlay :file:`k3-am62l3-evm-idle-states.dtso` disables the CPSW driver to ensure this
-   condition is met. Do not override this configuration without understanding the implications for cluster
-   idle transitions and hardware stability.
+This overlay adds the ``cluster_sleep_deep_stby`` idle state to the device tree configuration.


No need to mention this in power domain hierarchy list?

This gets added in the CLUSTER_PD domain itself

StaticRocket

I'd prefer if you defined the acronyms you use here, but I'm still evaluating some other solutions for this.

StaticRocket · 2026-07-20T18:26:36Z

+   | The ``cluster_sleep_deep_stby`` state is an optional configuration. Enable it using the device tree overlay
+     :file:`k3-am62l3-evm-idle-states.dtso`.
+   | It should be used **only** when CPSW and Display drivers are not needed.
+   | See :ref:`deep-standby-mode` for more details.


Please avoid using | unless explicitly necessary for formatting. It has a habit of breaking other directives.

StaticRocket · 2026-07-20T18:27:40Z

+
+   | The ``cluster_sleep_deep_stby`` state is an optional configuration. Enable it using the device tree overlay
+     :file:`k3-am62l3-evm-idle-states.dtso`.
+   | It should be used **only** when CPSW and Display drivers are not needed.


Suggested change

| It should be used **only** when CPSW and Display drivers are not needed.

| **Only do this when CPSW and Display drivers are not needed.**

StaticRocket · 2026-07-20T18:28:33Z

 * **CLUSTER_PD** (Cluster Power Domain): Cluster-level power domain that groups multiple CPUs

-These power domains inform CPUIdle about which non-critical domains can be disabled when all cores within them are idle.
+These power domains inform CPUIdle about which non-critical domains to disable when all cores within them are idle.


Suggested change

These power domains inform CPUIdle about which non-critical domains to disable when all cores within them are idle.

These power domains inform CPUIdle about what non-critical domains to disable when all cores within them are idle.

StaticRocket · 2026-07-20T18:33:40Z

 To monitor cluster-level standby mode usage, which is the most useful metric for verifying that the system
-is successfully entering the low-latency standby mode when all cores are idle:
+is successfully entering the standby mode when all cores are idle:


The cluster-level standby mode usage metric is useful metric for verifying that the system is successfully entering standby mode. To check this value, issue the following:

akashdeep-ti · 2026-07-21T05:40:18Z

-   * - **cluster_sleep_0** (Low Latency Cluster standby)
-     - Cluster low-latency standby mode when all cores are idle, with reduced clock frequencies and non-critical power domains disabled
+   * - **cluster_sleep_stby** (Cluster standby)
+     - The default Cluster standby mode when all cores are idle, with reduced clock frequencies and non-critical power domains disabled


i am still thinking that this chapter should list the exact hardware optimizations done, that is which clock frequency is reduced, which non-critical power domains are disabled and other system details, maybe a table with that. As the current information is not that useful to a reader because what is non-critical from our point of view may be critical for user.

kwillis01

Info looks good, mostly need updates for grammar. We should decide on how the states are named and their capitalization to stay consistent. Not sure if all my changes are vale approved, so try to do something similar to the changes if not.

kwillis01 · 2026-07-21T16:14:49Z

+   * - **cluster_sleep_deep_stby*** (Cluster Deep standby)
+     - Additional Deep standby mode similar to cluster standby, with additional clock gating and power domain shutdown for more aggressive power savings.


nit: why is deep capitalized? IMO needs to either be "Deep Standby" or "deep standby" when talking about the mode.

yes, ill follow this convention

kwillis01 · 2026-07-21T16:22:01Z

+   The ``cluster_sleep_deep_stby`` state is an optional configuration. Enable it using the device tree overlay
+   :file:`k3-am62l3-evm-idle-states.dtso`.
+
+   **Only do this when CPSW and Display drivers are not needed.**


Suggested change

**Only do this when CPSW and Display drivers are not needed.**

**Only enable deep standby mode when CPSW and Display drivers are not needed.**

kwillis01 · 2026-07-21T16:25:22Z

+----------------------

-The AM62L Standby Mode implementation has important prerequisites that must be met for correct operation.
+Meet the following prerequisites before using AM62L Deep Standby Mode.


nit

Suggested change

Meet the following prerequisites before using AM62L Deep Standby Mode.

The following prerequisites must be met before using AM62L Deep Standby Mode.

kwillis01 · 2026-07-21T16:28:50Z


-Similarly, the display driver must be in a suspended state for cluster standby due to frame buffer overflow issues.
-Ensure display is not actively driving output when testing or relying on Standby Mode for power savings.
+Similarly, the display driver must not drive output during Deep standby. The DDR enters Auto self-refresh


nit: capitalization

Suggested change

Similarly, the display driver must not drive output during Deep standby. The DDR enters Auto self-refresh

Similarly, the display driver must not drive output during deep standby. DDR enters auto self-refresh

kwillis01 · 2026-07-21T16:29:54Z

-   overlay :file:`k3-am62l3-evm-idle-states.dtso` disables the CPSW driver to ensure this
-   condition is met. Do not override this configuration without understanding the implications for cluster
-   idle transitions and hardware stability.
+To enable Deep Standby Mode, apply the device tree overlay :file:`k3-am62l3-evm-idle-states.dtso` to your system.


nit: capitalization

Suggested change

To enable Deep Standby Mode, apply the device tree overlay :file:`k3-am62l3-evm-idle-states.dtso` to your system.

To enable deep standby mode, apply the device tree overlay :file:`k3-am62l3-evm-idle-states.dtso` to your system.

kwillis01 · 2026-07-21T16:32:19Z

+
+   * - Mode
+     - Hardware Sequence Steps
+   * - **Default Standby Mode**


Maybe rename to "shallow standby mode"? "Default" isn't really descriptive imo and renaming to "shallow" will make it easier to talk about it in other sections

kwillis01 · 2026-07-21T16:33:29Z

+       * Put PLL8(A53 clock) in bypass
+   * - **Deep Standby Mode**
+     - * All default standby mode steps
+       * Reduce CBASS frequency to lowest functional value(125Mhz)


nit:

Suggested change

* Reduce CBASS frequency to lowest functional value(125Mhz)

* Reduce CBASS frequency to lowest functional value (125Mhz)

kwillis01 · 2026-07-21T16:33:45Z

+   * - **Deep Standby Mode**
+     - * All default standby mode steps
+       * Reduce CBASS frequency to lowest functional value(125Mhz)
+       * Put DDR in Auto-self-refresh


nit:

Suggested change

* Put DDR in Auto-self-refresh

* Put DDR in auto self-refresh

kwillis01 · 2026-07-21T16:35:34Z


-Once Standby Mode is enabled, you can monitor idle state activity through the PM generic power domain (genpd)
-sysfs interface. The power domain names are derived from the PSCI power domain hierarchy defined in the device
+Once you enable Standby Mode, you can monitor idle state activity through the PM generic power domain (genpd)


Suggested change

Once you enable Standby Mode, you can monitor idle state activity through the PM generic power domain (genpd)

Once the standby modes are enabled, you can monitor idle state activity through the PM generic power domain (genpd)

This might change it to passive voice, however it sounds correct this way.

kwillis01 · 2026-07-21T16:38:44Z


-To monitor cluster-level standby mode usage, which is the most useful metric for verifying that the system
-is successfully entering the low-latency standby mode when all cores are idle:
+The cluster-level standby mode usage metric is useful metric for verifying that the system


Suggested change

The cluster-level standby mode usage metric is useful metric for verifying that the system

The cluster-level standby mode usage metric is useful for verifying that the system

The existing standby mode is renamed from 'low-latency standby' to 'standby' and has been migrated to the default device tree from an overlay. A new 'deep-standby' mode has been added which requires the overlay for use. Update the docs to reflect these changes, introduce the new deep-standby mode along with its pre-requisites and how to enable the given mode. Signed-off-by: Scaria Kochidanadu <s-kochidanadu@ti.com>

ti-scaria requested review from StaticRocket, VeeruPrudhvi, cshilwant, gehariprasath, jeevantelukula, praneethbajjuri and uditkumarti as code owners July 17, 2026 13:00

github-actions Bot assigned devarsht, gehariprasath, praneethbajjuri, r-vignesh, ti-scaria, uditkumarti and vishalmti Jul 17, 2026

akashdeep-ti suggested changes Jul 20, 2026

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ti-scaria force-pushed the update_standby branch from 6b568d0 to f734092 Compare July 20, 2026 07:22

ti-scaria changed the title ~~fix(linux): Update AM62L standby mode docmentation~~ fix(linux): Update AM62L standby mode documentation Jul 20, 2026

akashdeep-ti reviewed Jul 20, 2026

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StaticRocket requested changes Jul 20, 2026

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akashdeep-ti reviewed Jul 21, 2026

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akashdeep-ti suggested changes Jul 21, 2026

View reviewed changes

ti-scaria force-pushed the update_standby branch from f734092 to b887dd7 Compare July 21, 2026 09:20

kwillis01 suggested changes Jul 21, 2026

View reviewed changes

ti-scaria force-pushed the update_standby branch from b887dd7 to ee32e83 Compare July 22, 2026 07:32

github-actions Bot requested review from devarsht, r-vignesh and vishalmti July 22, 2026 07:32

akashdeep-ti approved these changes Jul 22, 2026

View reviewed changes

	\| It should be used only when CPSW and Display drivers are not needed.
	\| Only do this when CPSW and Display drivers are not needed.

	These power domains inform CPUIdle about which non-critical domains to disable when all cores within them are idle.
	These power domains inform CPUIdle about what non-critical domains to disable when all cores within them are idle.

		* - cluster_sleep_deep_stby* (Cluster Deep standby)
		- Additional Deep standby mode similar to cluster standby, with additional clock gating and power domain shutdown for more aggressive power savings.

	Only do this when CPSW and Display drivers are not needed.
	Only enable deep standby mode when CPSW and Display drivers are not needed.

	Meet the following prerequisites before using AM62L Deep Standby Mode.
	The following prerequisites must be met before using AM62L Deep Standby Mode.

	Similarly, the display driver must not drive output during Deep standby. The DDR enters Auto self-refresh
	Similarly, the display driver must not drive output during deep standby. DDR enters auto self-refresh

	To enable Deep Standby Mode, apply the device tree overlay :file:`k3-am62l3-evm-idle-states.dtso` to your system.
	To enable deep standby mode, apply the device tree overlay :file:`k3-am62l3-evm-idle-states.dtso` to your system.

	* Reduce CBASS frequency to lowest functional value(125Mhz)
	* Reduce CBASS frequency to lowest functional value (125Mhz)

	* Put DDR in Auto-self-refresh
	* Put DDR in auto self-refresh

	Once you enable Standby Mode, you can monitor idle state activity through the PM generic power domain (genpd)
	Once the standby modes are enabled, you can monitor idle state activity through the PM generic power domain (genpd)

	The cluster-level standby mode usage metric is useful metric for verifying that the system
	The cluster-level standby mode usage metric is useful for verifying that the system

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