On 10.06.22 21:32, Sylvain Munaut wrote: > Hi, > > AFAICT the pps-ldisc support is done for proprietary USB serial > adapters (ch341/ftdi/pl2023/...) but is not supported for class The standard disclaimer would be that there is no such thing as a class for serial devices, so they are all proprietary. CDC-ACM uses the serial layer because that is how modems are traditionally attached to hosts, but basically it is a class for modems not for serial devices. The support for DCD is optional. > standard CDC-ACM devices ? Yes, currently cdc-acm does not call usb_serial_handle_dcd_change() if a DCD change message arrives. > Is that correct ? Did I miss something ? Well, technically you could attach the line disciplibe, but it would do nothing. Do you have a CDC-ACm device that can be used for PPS or is that a theoretical question? The necessary change is not large. Regards Oliver
