TI81XX PSP PM FAQ

TI81XX Linux PSP PM FAQ

Linux PSP

IMPORTANT

DM816x/AM389x family of devices referred as TI816X unless explicitly noted.
DM814x/AM387x family of devices referred TI814X unless explicitly noted.
Descriptions common across both the device families use the term TI81XX.

General

What are various Linux PSP power management support status for TI81XX devices?

Following table lists various Power Management (PM) features supported in PSP Linux on TI81XX:
Note: For corresponding features, N/A in the field means no h/w support, TBD means the feature is planned to be implemented, NO indicates features unplanned

Feature	TI816X	TI814X	TI813X	TI811X	Notes
Clock control	YES	YES	YES	YES	Provides kernel level clock control APIs. Allows drivers to enable/disable module clocks as per the need to save active power. Refer Clock framework user guide
AVS	YES	TBD	TBD	TBD	Refer AVS User Guide
Suspend to RAM	NO	YES	YES	TBD	Refer TI814X suspend/resume guide
DeepSleep	NA	YES	YES	TBD	Refer TI814X suspend/resume guide
DVFS	N/A	YES	TBD	TBD	Refer TI814X DVFS user guide
CPUIdle	NO	NO	NO	NO	WFI (ARM Cortex - A8 in low-power standby state) on idle is supported.

Note: Subsequent sections and questions are only applicable for platforms which support the respective features as shown in above table

Suspend to RAM

This section is applicable only for TI814X devices.

Does the system suspends automatically during normal execution?

No. Suspend to memory operation is triggered by user command. See next question below.

How do I initiate suspend to RAM?

To initiate suspend to memory (RAM) execute following command at root shell:

# echo -n "mem" > /sys/power/state

Currently on TI814X platforms, this results into system suspending to RAM.

How does the system wake up from suspend

System resumes operation when woken up on activity from one (or many) of the wake-up sources, such as pressing a keyboard key on console.

What all wakeup sources possible for TI814X?

Events on following modules can wakeup up the suspended TI814X device:

• Timer
  • Wakeup on specified timeout after suspend
• UART
  • Wakeup on detecting keystroke on UART console. Note that on EVM, UART0 is used as console.