fix(unix): handle unsupported modem-control ioctls on Linux#235
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dcodeIO wants to merge 1 commit intoserialport:mainfrom
Open
fix(unix): handle unsupported modem-control ioctls on Linux#235dcodeIO wants to merge 1 commit intoserialport:mainfrom
dcodeIO wants to merge 1 commit intoserialport:mainfrom
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Improve Linux modem-control compatibility by handling unsupported ioctl cases in set() without failing valid RTS/DTR updates (e.g. WSL with usbipd-attached devices).
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Potentially related: #229 (similar "Operation not supported" symptoms) |
This was referenced Feb 17, 2026
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Ran into this while attempting to flash an ESP32 from WSL with the device attached via usbipd, where serialport set() returned "Operation not supported" when toggling modem-control lines used to reset into bootloader. With this change, rebooting into bootloader via DTR/RTS works as expected.
Used pyserial (which works in the same setup) as a reference:
Ignores unsupported ioctl errors (EINVAL, ENOTTY) when applying initial modem state:
https://github.com/pyserial/pyserial/blob/911a0b8c110f3d3513bab67e64d95d1310517454/serial/serialposix.py#L347-L355
Uses per-bit modem control (TIOCMBIS / TIOCMBIC) for RTS and DTR:
https://github.com/pyserial/pyserial/blob/911a0b8c110f3d3513bab67e64d95d1310517454/serial/serialposix.py#L751-L763