STM32 Power Management Roadmap

[erwango]

Umbrella ticket to track power management related activities.
Aim is to STM32 related tickets/PR, but also cross-architectures tickets that might be relevant to enable power management use cases on STM32.

Strategy

There will be 2 mains tracks of power management on STM32 series depending on SoCs ability to handle low power use cases, roughly:

• LP enabled series , supporting LPTIMER and ability to wake-up from sleep modes
• Non LP enabled series on which will restrict PM handling to standby use cases

Current view

• Support LPTIM as tick source that can be used to wake up from sleep mode
  • Implementation on L4 series (lptim: stm32l4: support of the lptimer #18582)
  • Extend to other LP series (WB: lptim: stm32wb: support of the lptimer #19881, G4: lptim: stm32g4: support of the lptimer on stm32g4xx #19879)
• Provide PM states description and PM states management samples : #stm32 sample application to test low power modes #26002
  • Implementation on L4 series (power: stm32l4: support of the Low Power Mode #19026)
    • Known limitations: No PLL resumption after wake up from sleep mode. Limited to fixed clocks
  • Extension to WB (power: stm32wb: support of the Low Power Mode  #20155) + power: stm32wb: support of the Low Power Mode hal_stm32#24
  • Implementation on F4 series
  • Extend to other series
• Configure wake up sources (pins or peripheral)
  • pins:
    • Propose a device tree representation (dts: Provide analog configuration for each pin hal_stm32#126)
    • Implement within driver
  • peripheral: Provide capability to configure alternate source clock ([RFC] stm32: clock_control: Enable device clock source selection #45053)
  • peripheral: Get system PM to take into account wake up source lowest supported power mode (pm: Miss a way to notify devices about wakeup source activation #39312)
  • peripheral: Dependencies with PM: Simplify device power states #38619
• Resume PLL after wake up from sleep mode (need to rerun stm32_clock_control_init) ([stm32] PM restore console after sleep mode #32128)
• Peripheral low power modes
  • STM32WL I2C doesn't work with LPM #37414
  • STM32WL ADC doesn't work with power management #37352 (STM32: using SPI after STOP2 sleep causes application to hang #50426)
  • stm32: uart: Support for wakeup from stop #43135

To follow closely

Power Management Infrastructure (#14307)

Should fix

[x] #14066

[erwango]

@FRASTM

[r2r0]

@erwango
Do you consider STM32WB55 as a member of L4 series or as a separate work for future?

[erwango]

@erwango
Do you consider STM32WB55 as a member of L4 series or as a separate work for future?

@r2r0, STM32WB55 is not part of STM32L4, but HW is actually quite close so we'll quickly extend PM support to it.

[gon1332]

@erwango @FRASTM

Since #18582 and #19881 are merged the progress should be updated.

[FRASTM]

In this issue, the low power modes of the stm32 soc series depend on the CONFIG_SYS_POWER_MANAGEMENT.

[FRASTM]

The low power control is being added to the drivers:
uart_stm32_pm_control

[FRASTM]

When exiting the low power mode, the device is restoring its clock with stm32_clock_control_init
in the pm_power_state_exit_post_ops function

[FRASTM]

Now supporting the low power modes (STOP0/1/2) on the stm32L5xx soc series (disco kit stm32l562e_dk board)
using the LPTimer(#32999) : PR #33131

[ycsin]

@erwango @FRASTM would it be possible to list down STM32 PM related functions in the drivers that are yet to be implemented? i.e. peripheral WKUP from STOP? It is easier to identify areas that needs more work this way.