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Fix working with CDC-ACM (ttyACMx) / CH347T

Open Azq2 opened this issue 4 months ago • 1 comments

Currently, we have a serious problem with all CDC-ACM serial ports. For example, with the very popular USB-to-RS232 adapter CH347T:

  serialport/stream binding.set had an error [Error: Error: Operation not supported, cannot set] +1ms

We cannot set any modem control signals because the BRK signal is optional in CDC-ACM implementations. See the Linux CDC-ACM driver source: https://github.com/torvalds/linux/blob/6fab32bb6508abbb8b7b1c5498e44f0c32320ed5/drivers/usb/class/cdc-acm.c#L930

A good solution is simply to ignore the ioctl error if it's EOPNOTSUPP. Example: https://github.com/torvalds/linux/blob/2e590d67c2d803d603ac00b85f2fab235df52a1b/drivers/tty/tty_io.c#L2486

Azq2 avatar Oct 24 '25 19:10 Azq2

:(

Azq2 avatar Nov 12 '25 12:11 Azq2

@reconbot this is still critical issue

Azq2 avatar Nov 29 '25 09:11 Azq2