From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga06.intel.com ([134.134.136.31]:57528 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727773AbeLEJg4 (ORCPT ); Wed, 5 Dec 2018 04:36:56 -0500 Subject: Re: [PATCH] USB: serial: console: fix reported terminal settings To: Johan Hovold , Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, Jiri Slaby , linux-kernel@vger.kernel.org, stable , Florian Zumbiehl References: <20181204155904.GC18087@localhost> <20181204160036.24625-1-johan@kernel.org> <20181204161518.GA17941@kroah.com> <20181204163155.GD18087@localhost> From: Jarkko Nikula Message-ID: <4e395eb4-739a-05df-e14d-e32f9cfefdd3@linux.intel.com> Date: Wed, 5 Dec 2018 11:36:52 +0200 MIME-Version: 1.0 In-Reply-To: <20181204163155.GD18087@localhost> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org List-ID: 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 # 4.18 >>> Reported-by: Jarkko Nikula >>> Cc: Florian Zumbiehl >>> Signed-off-by: Johan Hovold >>> --- >>> 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