On 12/4/18 6:31 PM, Johan Hovold wrote:
On Tue, Dec 04, 2018 at 05:15:18PM +0100, Greg Kroah-Hartman wrote:
On Tue, Dec 04, 2018 at 05:00:36PM +0100, Johan Hovold wrote:
The USB-serial console implementation has never reported the actual
terminal settings used. Despite storing the corresponding cflags in its
struct console, this was 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()
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: 7041d9c3f01b ("USB: serial: pl2303: add support for tx xon/xoff flow control")
Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.18
Reported-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
Cc: Florian Zumbiehl <florz@xxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/tty/tty_io.c | 11 +++++++++--
drivers/usb/serial/console.c | 2 +-
include/linux/tty.h | 1 +
3 files changed, 11 insertions(+), 3 deletions(-)
Ah, messy :)
Want me to take this through my tty tree?
If you prefer. I was planning on including this in a USB-serial pull
request for -rc6 since it fixes a user-reported regression, but perhaps
taking this through your tty-linus branch (which already holds a console
fix) is easier/faster.
We should wait for Jarkko to confirm that this fixes the problem he
reported first, though.
Great, this fixed the issue for both pl2303 based adapters I reported.
Tested on top of 0072a0c14d5b ("Merge tag 'media/v4.20-4' of
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media")
Tested-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
