08:07 <michalkotyla> Hi, I'm trying to apply this patch https://review.openocd.org/c/openocd/+/2148/ for imx8m. It works for me on imx6, now I try to do this same on better imx soc. Maybe someone has experience in that and confirms (or rejects) if I understand this correctly: in target/imx8m.cfg I can see TAPID for DAP, for reading challenge and sending response key I

08:07 <michalkotyla> need to access SJC. It generally should work when I add SJC target to imx8m.cfg like here: https://review.openocd.org/c/openocd/+/2148/1/tcl/target/imx6.cfg ? I mean, it should be not a problem working with DAP and SJC in this same session?

08:09 <PaulFertser> michalkotyla: SJC is on a different _tap_ right? And DAP is an ARM-specific debug block which you access using a dedicated _tap_.

08:11 <PaulFertser> michalkotyla: so there's a JTAG chain, it can have many taps. And hardware uses certain taps for certain functions. Some SoCs have "jtag routers" which allow to connect and disconnect taps from the chain but the tap used to control the router itself always stays.

08:14 <PaulFertser> michalkotyla: if SJC isn't present on the chain then it's just not there, you can't talk to it. You need to read the SoC datasheet to find how to enable it.

08:16 <michalkotyla> PaulFertser: yes, SJC has a different TAP id. DAP is a ARM-specific debug block with id 0x5ba00477, this same like in many other SoCs. Ok, now it is more clear for me - thanks

08:19 <PaulFertser> michalkotyla: you can try starting OpenOCD without target config and you'll see TAP autodetection.

08:19 <PaulFertser> michalkotyla: for imx8m I expect you to see only the TAPs attached to DAPs (assuming upstream target config normally works)

08:21 <PaulFertser> If SJC is not on the list it means you need to do something with the hardware (strap resistors?) for it to appear.

08:25 <michalkotyla> PaulFertser: OpenOCD see only 0x5ba00477 (ARM DAP) and 0xffffffff (error value?), so it must be something with the hardware - I need to change JTAG_MOD and I will try that