How to boot imx8mm M4 as early as possible?

[greg_edwards]

Using an imx8mm I need to boot the M4 as quickly as possible.  Using u-boot scripting with a 0 autoboot abort delay gets me below 3 seconds but we need to get faster than that.

The plan is to open up u-boot to load and run the M4 immediately before the autoboot abort delay.  Does anyone have any advice on going down this path?

TIA

[greg_edwards]

If the M4 is brought out of reset before u-boot runs can it execute from SPI Flash?  If so, is it possible to program the SCU to start the M4?  I haven't drilled down in the SCU code yet.

[b36401]

No. There is no such option in i.MX8M series.
Sorry for the inconvenience.

[b36401]

You can load your M4 program to the memory with fatload u-boot command and then start M4 core with bootaux command.

[greg_edwards]

The u-boot script doesn't run until after the autoboot abort option delay expires.  Using this method takes 2+ seconds to get to the abort prompt plus any delay at the prompt before the command can start running.  I need to boot the M4 before the prompt.

[b36401]

I am afraid there is no easy way to boot M4 core early without changing u-boot logic.
However we have no suggestions to add booting M4 core in the very beginning of u-boot.
Sorry for the inconvenience.