iMX8: M4 stops running on A53 reset

[takahisa_tanaka]

Hello

I experienced that M4 stops running, after a 'reboot' command on A53.
According to the thread below, after reset, A7 will reconfigure the clocks on which M4 is depending and this may cause unknown behaviors.

iMx7: M4 stops running on A7 reset
https://community.nxp.com/thread/442858

Does A53, like A7, reconfigure the clock on which M4 is depending?

Regards,
Takahisa Tanaka

[igorpadykov]

Hi Takahisa

>Does A53, like A7, reconfigure the clock on which M4 is depending?

yes

Best regards
igor
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[takahisa_tanaka]

Hi Igor,

When I was investigating the code in imx-atf in another matter, I noticed that the reboot command would not stop M4, because the reboot command fires the watchdog(timeout 500ms) and does a full reset.

When I reviewed my test environment, the RTOS image was not loaded on M4 after reboot due to a U-boot misconfiguration.

Sorry, i.MX8 does not stop M4 after reboot.

Best Regards,
Takahisa Tanaka

[takahisa_tanaka]

Hi Igor,

> Sorry, i.MX8 does not stop M4 after reboot.

No. I was mistaken in my understanding. M4 stops running on A53 reset.

Executing the reboot command takes a full reset with watchdog, so M4 boots after it stops.

Sorry for the confusion.

Best Regards,
Takahisa Tanaka

[takahisa_tanaka]

Hi igor

Thank you for your quick response!

Regards,

Takahisa Tanaka