Booting M4 freeze linux kernel A7

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Booting M4 freeze linux kernel A7

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maitegonzalez
Contributor I

Hello,

I am trying to boot the M4 core on imx7dual  (Through emmc).

 

When the M4 boot (hello world example), the linux kernel blocks. (Starting kernel)

I changed the following environment variables in the uboot and try to boot the system:

=> setenv loadm4image 'fatload mmc ${mmcdev}:${mmcpart} 0x7F8000 ${m4image}'

=> setenv m4boot 'if run loadm4image; then setenv mcu -m4; dcache flush; bootaux 0x7F8000; fi'

=> setenv setfdt 'setenv fdt_file ${som}_${baseboard}${mcu}.dtb'

=> setenv mmcboot 'echo Booting from mmc ...; run m4boot; run searchbootdev; run mmcargs; echo baseboard is ${baseboard}; run setfdt; if test ${boot_fdt} = yes || test ${boot_fdt} = try; then if run loadfdt; then bootz ${loadaddr} - ${fdt_addr}; else if test ${boot_fdt} = try; then echo WARN: Cannot load the DT; echo fall back to load the default DT; setenv baseboard $ {default_baseboard}; run setfdt; run loadfdt; bootz ${loadaddr} - ${fdt_addr}; else echo WARN: Cannot load the DT; fi; fi; else bootz; fi;'

Then, execute "boot". At this point, I am able to see the console prompt of the M4, but the linux blocks (Starting kernel).

I dont know, is it posible to be something related to some reset bit, o some watchdog which I have to disable??

Thank you in advance!

Maite

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art
NXP TechSupport
NXP TechSupport

Please note that the A7 core(s) of the i.MX7 series processors is always supposed to boot first, then load and run the M4 core, then, for example, go to the low-power mode as required and then be awaken up by the M4 core also as required.

For example, please refer to the AN5317 "Loading Code on Cortex-M4 from Linux for the i.MX 6SoloX and i.MX 7Dual/7Solo Application Processors" Application Note document, available on the processor's Documentation web page:

https://www.nxp.com/products/microcontrollers-and-processors/arm-based-processors-and-mcus/i.mx-appl...

Also, refer to the attached documents, describing the FreeRTOS BSP for the M4 core operation.


Have a great day,
Artur

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Carlos_Musich
NXP Employee
NXP Employee

Hi Maite,

- Are you able to start linux kernel in Cortex A7 if you dont start M4 first?

- Are you able to start M4 afetr starting linux kernel in Cortex A7?


Regards,
Carlos

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maitegonzalez
Contributor I

Hello,

Thanks for answering. 

Yes, if I dont start M4, I am able to start the cortexA7 normally. 

I didn't try to boot m4 after starting linux kernel.. How would it be? writing the registers to restart the M4 with mmap?

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Carlos_Musich
NXP Employee
NXP Employee

Hi Maite,

I am very sorry, I thought I have already answered. Please see the following document, it explains all the settings required to run RPMsg examples which communicates A7/A9 with M4, so this will help.

Running RPMsg Demo Applications for Multicore Communication with IMX6SX and IMX7D 


Regards,
Carlos

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maitegonzalez
Contributor I

Hello,

Thank you for your answer. We finally achieved to start both M4 and A7. We were doing OK.

However, we are using one of technexion SOM and it seems something is wrong in the WI-FI module. 

I mean, we have the same firmware and in the WI-FI module the A7-core blocks when M4 starts and without WI-FI the module works perfectly (M4-A7).

I don't know what is going on

Regards,

Maite

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