probe-rs on LPC-Link2 v1.0.7: SWD-attach layer quirks (#930 follow-up)

[zackees]

Split-out of #930 (now closed).

Scope

Once the DAP_Info init sequence passes (parent umbrella closed for blockers 1-3 via FastLED/probe-rs#1 and its serial-number follow-up), probe-rs advances to actual SWD attach: DAP_Connect, DAP_TransferConfigure, DAP_SWJ_Sequence, and the AP/DP read/write commands.

The LPC-Link2 v1.0.7 firmware likely has more quirks in this layer — specifically:

• DAP_Connect(port=SWD) may not correctly report the negotiated port back
• Wait / retry semantics on DAP_Transfer are known-flaky on this firmware generation
• Idle cycle counts may need to be dialed down for reliability

Each blocker follows the same "log-and-fall-back" pattern established in FastLED/probe-rs#1.

Discovery loop

• Run `RUST_LOG=probe_rs::probe::cmsisdap=trace probe-rs info --chip LPC845M301JBD48 --probe 1fc9:0132` (once blockers 1-4 close), capture the first new failure signature.
• Add a fallback for it in the FastLED/probe-rs fork.
• Repeat until `probe-rs run --chip LPC845M301JBD48 firmware.hex` succeeds against the physically-attached LPC845-BRK.

Acceptance

probe-rs run --chip LPC845M301JBD48 --probe 1fc9:0132 <firmware.hex> writes flash and resets the target without any hardware button press.

Related

• probe-rs on LPC-Link2 CMSIS-DAP v1.0.7: series of upstream quirks to patch through #930 (parent umbrella, closed)
• FastLED/probe-rs#1 (blockers 1-3 landing PR)
• fbuild deploy: own nxplpc/LPC8xx flash end-to-end (FastLED is removing its direct pyocd path) #921 (parent tracking issue for LPC845-BRK end-to-end deploy)