How to power on the M4 subsystem

[xiaokaoy]

Hello,

I'm using i.mx8dual, and I'm trying to start M4 from u-boot using the bootaux command, but it seems that the u-boot doesn't even have access to the memory at 0x34FE0000, which is TCM of M4. Reading the TCM will cause a crash, as shown below:

=> md.b 0x34FE0000 0x100
34fe0000:"Synchronous Abort" handler, esr 0x96000210
elr: 0000000080060d5c lr : 0000000080060c74 (reloc)
.....

Code: 12003c42 783c7b62 92403c42 17ffffeb (39400062)
Resetting CPU ...

I thought that was just due to the following code in the board_system_config function

BRD_ERR(rm_find_memreg(pt_boot, &mr_m4_0, 0x034FE0000ULL,
0x034FE0000ULL));
BRD_ERR(rm_assign_memreg(pt_boot, pt_m4_0, mr_m4_0));

so I commented them out. But it still didn't work. Afterwards, I found that sc_fw_port.pdf says "Code loading will require the M4 subsystem already be powered on", so I added

BRD_ERR(pm_set_resource_power_mode_all(pt_boot, pt_m4_0, SC_PM_PW_MODE_ON, SC_R_LAST));

to the end of the board_system_config function. However, this caused my CPU to halt even before running u-boot.

Isn't pm_set_resource_power_mode_all what should be called to power on the M4 subsystem?

[xiaokaoy]

Thanks for the reply. But when I clicked on the link, I got this message:

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[joanxie · Accepted solution]

it seems this document is internal, I couldn't share this in the public community, you can refer to the link as below:

"https://community.nxp.com/t5/i-MX-Processors/Boot-Partition-Problem-to-start-M4-as-a-remote-proccess..."

[joanxie]

I think this document is very useful for you

"https://community.nxp.com/t5/iMX-and-Vybrid-Support/M4-partition-booted-reset-from-A-Cortex-Software...