unaddressed issues around tty_open_by_driver

[Samuel Thibault]

Okash Khawaja, on mar. 27 juin 2017 10:44:45 +0100, wrote:
> Next, I think, we need to restore tty->termios.c_line to the ldisc
> before speakup was loaded, because that's what is used when opening tty
> [1]. Locally, I have done that by caching original ldisc and then
> calling tty_set_termios_ldisc on module exit which resolves that issue.
> However, in kernel tty_set_termios_ldisc is static function and will
> need to be exported if we want to call it.

Mmm, it looks odd to be doing such kind of hackery. It'd probably be
good to check how other line disciplines are doing.

Samuel