Hi Mathieu and Youngjae,
Yes, I can try to help to debug this.
I was in contact earlier last week with Youngjae about enabling collection of ETM traces on their device, and I asked them to send a message to the list.
I got their perf.data and it seems like there are no ETM events when they record with perf from the 4.9 branch.
On the other hand the perf.data collected with the 4.12 branch seems to contain ETM trace events and the decoder seems to die on initialization when injecting.
I'm not sure whether that is related to support in the coresight decoder for ETM v4.2.
I will need to dig a little more with gdb.
Sebastian