Reduce MCUBoot startup time

[Yeccc]

We found that it took a long time for the nrfconnect sdk to power on the device to enter the application.
Is there any way to reduce the startup time?

We have closed the log, and the startup time has reached 1.3s.
It is too long for the bulb device, so we need to solve this issue.

[Yeccc]

The bulb device needs to be on soon after being powered on;

In addition, our bulb device is restored to factory settings through multiple power on/off sequences, and too long startup time will also affect the user experience.

I really hope you can solve this issue. Thanks a lot.

[Vidar Berg]

Thank you for explaining the reason you are looking to reduce the startup time. This is valuable feedback which I will relay to the developers. 

I was able to significantly reduce the startup time now by disabling boot validation that takes place on every reboot by default, and by changing the default clock configuration.

Here are my results:

#1 with RCOSC as LF clock source

Settings added to MCUBoot build:

- CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

- CONFIG_BOOT_VALIDATE_SLOT0=n

In light bulb app:

 

- CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

#2 with LFXO as LF clock source

Settings added to MCUBoot build:

- CONFIG_SYSTEM_CLOCK_WAIT_FOR_STABILITY=n

- CONFIG_BOOT_VALIDATE_SLOT0=n

In light bulb app:

 

- CONFIG_SYSTEM_CLOCK_WAIT_FOR_STABILITY=n

You may also consider using the SYS_INIT() macro for functions that may benefit from being run before main().

[Yeccc]

Thanks for your support.

Does this have any other impact?

[Yeccc]

Could you confirm it?
Does this modify have other effects?

[Vidar Berg]

Which configuration did you want to use, the one with LFXO or LFRC?