stm32wlx: SWOTrace not working

[thornley-permaconn]

I have been evaluating the nucleo-wl55jc1 and have deployment and debugging working via openocd (just single core at the moment). I am currently running "xPack Open On-Chip Debugger 0.12.0+dev-01312-g18281b0c4-dirty (2023-09-04-22:31)" a very recent build by xPack.

We use SWOTrace quite extensively, especially on devices that lack UART peripherals, however I have had trouble getting it to work with target/stm32wlx.cfg. My complete configuration derived from other working f1x, f4x, l4x parts : -

`source [find interface/stlink.cfg]

transport select hla_swd

source [find target/stm32wlx.cfg]

itm port 0 on
tcl_port 6666

tpiu create stm32wlx.cpu0.tpiu -dap stm32wlx.dap -ap-num 0
stm32wlx.cpu0.tpiu configure -protocol uart -traceclk 32000000 -output swo_out -formatter off -pin-freq 1000000
stm32wlx.cpu0.tpiu enable
`

Using this configuration SWOTrace only works if I enable and use it with STMCubeIDE first, this only seems to work with the "ST-LINK (ST-LINK GDB Server)" debug probe using the SWV capabilities of the IDE. I couldn't get "ST-LINK (openocd)" to work at all. The device will then work fine with SWOTrace until I remove power to the device. I suspect there are missing register changes in the openocd configuration, this might have something to do with the dual-core nature, but I did look at scripts for other parts like stm32wb but didn't notice anything different.

Note that I found that SB8 on the dev board requires a solder bridge for SWO to be passed to the built-in STLink device.