QtSerialPort not working with USB serial printer on Linux

I have an EPSON TM-9T88V printer. The printer has a USB interface which shows up on Linux as a printer device:

crw-rw---- 1 root lp 180, 1 Feb 16 15:27 /dev/usb/lp1

I am able to communicate with the printer device as if it was a serial port from shell commands or minicom. But when opening the device using QSeriaLport::open() , it fails with the error "Inappropriate ioctl for device".

I suspect there is a check somewhere for the device being a tty or it is trying to set a parameter like the baud rate which is not supported.

Maybe this isn't really a Qt bug since it is not a true serial port, but it would be very useful if I could use QSerialPort with this device and not have to use OS-level APIs.

Could you point me to the code in QSerialPort that might be causing this to fail?