• Johan Hovold's avatar
    USB: serial: console: fix reported terminal settings · f51ccf46
    Johan Hovold authored
    The USB-serial console implementation has never reported the actual
    terminal settings used. Despite storing the corresponding cflags in its
    struct console, these were never honoured on later tty open() where the
    tty termios would be left initialised to the driver defaults.
    
    Unlike the serial console implementation, the USB-serial code calls
    subdriver open() already at console setup. While calling set_termios()
    and write() before open() looks like it could work for some USB-serial
    drivers, others definitely do not expect this, so modelling this after
    serial core is going to be intrusive, if at all possible.
    
    Instead, use a (renamed) tty helper to save the termios data used at
    console setup so that the tty termios reflects the actual terminal
    settings after a subsequent tty open().
    
    Note that the calls to tty_init_termios() (tty_driver_install()) and
    tty_save_termios() are serialised using the disconnect mutex.
    
    This specifically fixes a regression that was triggered by a recent
    change adding software flow control to the pl2303 driver: a getty trying
    to disable flow control while leaving the baud rate unchanged would now
    also set the baud rate to the driver default (prior to the flow-control
    change this had been a noop).
    
    Fixes: 7041d9c3 ("USB: serial: pl2303: add support for tx xon/xoff flow control")
    Cc: stable <stable@vger.kernel.org>	# 4.18
    Cc: Florian Zumbiehl <florz@florz.de>
    Reported-by: default avatarJarkko Nikula <jarkko.nikula@linux.intel.com>
    Tested-by: default avatarJarkko Nikula <jarkko.nikula@linux.intel.com>
    Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
    f51ccf46
console.c 7.13 KB