Meaning of m4_tcm in device-tree

[georgefff]

Hi all,

I was wondering what was the use of including node "m4_tcm" in the device-tree. I know that is used to tell kernel to have knowledge about the M4 core but..

What should I use in device-tree if I link the M4's firmware in the OCRAM? Should I maintain the "m4_tcm" in the device-tree? In that case, should I disable &ocram node in device-tree?

Thanks in advance

[igorpadykov]

Hi George

if M4's firmware is in the OCRAM, device-tree can be changed accordingly.

Note it is already used in dts by linux, so one can try to disable &ocram node:

imx7d-sdb-m4.dtsi\dts\boot\arm\arch - linux-imx - i.MX Linux kernel 

Memory usage is described in AN5317 Loading Code on Cortex-M4 from Linux for the i.MX 6SoloX and

i.MX7Dual/7Solo Application Processors
https://www.nxp.com/docs/en/application-note/AN5317.pdf 

Best regards
igor
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[georgefff]

Thank you for your fast response and for attached document.

Nevertheles, I can't figure out the purpose of m4_tcm in the device tree. I read somewhere that it's just for kick the M4 MCU from Linux, that's why I'm asking for it's usage even with OCRAM/DDR

Regards