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probe: cmsis-dap: skip zero-length USB IN packets - #2061
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RobertRostohar wants to merge 2 commits into
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Some CMSIS-DAP v2 probes append a ZLP after a full-size response, causing it to be interpreted as the next command's response.
RobertRostohar
requested review from
TeoMahnic
and
a balanced review from Copilot
October 19, 2026 05:52
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🟢 Approval recommended
The focused change preserves response ordering, token accounting, shutdown handling, and existing error propagation.
No open issues 🎉
What changed in this PR
Fixes CMSIS-DAP v2 response handling so trailing zero-length USB packets are not mistaken for command responses.
Changes:
- Retries empty reads without consuming another read token, while preserving shutdown checks.
- Removes an unused import and reformats the SWO read call.
| File | Description |
|---|---|
pyocd/probe/pydapaccess/interface/pyusb_v2_backend.py |
Skips empty USB responses and cleans up surrounding code. |
Review effort: Balanced
TeoMahnic
approved these changes
Oct 19, 2026
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Some CMSIS-DAP v2 probes append a ZLP after a full-size response, causing it to be interpreted as the next command's response.