Modem line flags are defined in <asm/termios.h> but i can't
find where (TIOCM_ST, TIOCM_SR) are used. get_modem_info() in
serial.c uses other flags but no these two ones..
So, why are they defined ? Can we just add a test in get_modem_info()
to report ST & SR ?
They're defined because it's part of the complete TIOCMGET interface.
However, not all hardware, and therefore not all driver, implementations
can support the entire TIOCMGET interface. Specifically, the standard
National Semiconductor 16450/16550/et. al. UART doesn't support the
secondary transmit and secondary receive RS-232 signals.
Sure, you can "just add a test" --- assuming that the hardware has
something you can test agsainst! :-)
- Ted