Zephyr power management enhancement plan

[bjarki-andreasen]

Introduction

This issue documents and tracks the changes needed to refactor PM device to achieve what is proposed in #84049.

High level steps

1. Use power domains/devices to dictate system state constraints instead of system state controling power domains/devices PM_DEVICE_POWER_DOMAIN refactor #89372

2. Replace uses of PM_DEVICE_SYSTEM_MANAGED with PM_DEVICE_RUNTIME in all applications.

3. Remove PM_DEVICE_SYSTEM_MANAGED. The system state will not be used to manage devices, this option therefore has no utility, and shall be removed.

4. Remove pm_device_runtime_enable() and the zephyr,pm-device-runtime-auto devicetree property. All devices will be managed by PM_DEVICE_RUNTIME if enabled, disabling it per device is not a valid pm device configuration.

5. Clean up all device drivers. This includes the following:

   • Use pm_device_driver_init() instead of calling pm_device_runtime_enable(), pm_device_init_suspended() etc.
   • Use pm_device_runtime_ APIs for resuming device dependencies like busses, pwms, etc, from device drivers.

   note: we will not remove inline calls to self get/put in can_start() or i2c_transfer() until step 7.

6. Adjust subsystems and applications (samples) which currently use pm_device_action_run to solely use pm_device_runtime APIs.

7. Remove inline self get/put calls from device drivers, like often present in can_start()/can_stop() or i2c_transfer(). These are no longer needed as applications/subsystems are mandated to call these APIs before and after using the device.

[ceolin]

@bjarki-andreasen thanks for creating it. From my understanding it is missing creating power domains for internal devices, otherwise those devices won't never know when they are powered off. Other than that is looking great.

[bjarki-andreasen]

@bjarki-andreasen thanks for creating it. From my understanding it is missing creating power domains for internal devices, otherwise those devices won't never know when they are powered off. Other than that is looking great.

Right! that is step actually step 1 :)

[ceolin]

@bjarki-andreasen thanks for creating it. From my understanding it is missing creating power domains for internal devices, otherwise those devices won't never know when they are powered off. Other than that is looking great.

Right! that is step actually step 1 :)

Ah cool, I thought it was just referring to current ones.

[nashif]

7. Remove inline self get/put calls from device drivers, like often present in can_start()/can_stop() or i2c_transfer(). These are no longer needed as applications/subsystems are mandated to call these APIs before and after using the device.

I am not following this change, this is a pillar and a fundemntal deisgn of runtime device power management. Need more information and details about this change and what does it fix/provide.

I think I understand some of the other items, but there need to be some more details and probably we need an overview of the overall power management architecture, why those changes are needed and where we will end up and if anything else is going to follow or if those changes get us where want to be.

[bjarki-andreasen]

7. Remove inline self get/put calls from device drivers, like often present in can_start()/can_stop() or i2c_transfer(). These are no longer needed as applications/subsystems are mandated to call these APIs before and after using the device.

I am not following this change, this is a pillar and a fundemntal deisgn of runtime device power management. Need more information and details about this change and what does it fix/provide.

I think I understand some of the other items, but there need to be some more details and probably we need an overview of the overall power management architecture, why those changes are needed and where we will end up and if anything else is going to follow or if those changes get us where want to be.

See the parent issue #84049 for details. This issue just describes the how, not the why :)

[decsny]

Would the busy status indication have any use or be removed along with system managed device PM ?