samd: timeout when connecting to samc21

[Koen De Vleeschauwer]

Attached the bmda output when connecting to an atsamc21.
blackmagic -tv 5 was run twice.
The first time there is a 2 second delay; the second time response is instantaneous.
log.txt

[Rachel Mant]

Interesting.. both succeeded, despite the warning about failing to halt the CPU.

Our bad though that we said -v 5 and should have asked for -v 29 so we get the full ADIv5 conversation - could you recapture the two traces at this higher verbosity level please?

[Koen De Vleeschauwer]

OK. blackmagic -tv 29, run twice. Log attached.
log2.txt

samd.c has some routines that look like workarounds for errata.. e.g. "Only required for SAM D20 Revision B Silicon". samc21 errata are here.