| Message ID | 20230301075751.43839-1-lma@semihalf.com |
|---|---|
| State | New |
| Headers | show |
| Series | serial: core: fix broken console after suspend | expand |
On Wed, Mar 01, 2023 at 08:57:51AM +0100, Lukasz Majczak wrote: > Re-enable the console device after suspending, causes its cflags, > ispeed and ospeed to be set anew, basing on the values stored in > uport->cons. The issue is that these values are set only once, > when parsing console parameters after boot (see uart_set_options()), > next after configuring a port in uart_port_startup() these parameteres > (cflags, ispeed and ospeed) are copied to termios structure and > the orginal one (stored in uport->cons) are cleared, but there is no place > in code where those fields are checked against 0. > When kernel calls uart_resume_port() and setups console, it copies cflags, > ispeed and ospeed values from uart->cons,but those are alread cleared. > The efect is that console is broken. > This patch address this by preserving the cflags, ispeed and > ospeed fields in uart->cons during uart_port_startup(). > > Signed-off-by: Lukasz Majczak <lma@semihalf.com> > Cc: stable@vger.kernel.org > --- > drivers/tty/serial/serial_core.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 2bd32c8ece39..394a05c09d87 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -225,9 +225,6 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, > tty->termios.c_cflag = uport->cons->cflag; > tty->termios.c_ispeed = uport->cons->ispeed; > tty->termios.c_ospeed = uport->cons->ospeed; > - uport->cons->cflag = 0; > - uport->cons->ispeed = 0; > - uport->cons->ospeed = 0; > } > /* > * Initialise the hardware port settings. > -- > 2.39.2.722.g9855ee24e9-goog > What commit id does this fix? thanks, greg k-h
On Wed, 1 Mar 2023, Lukasz Majczak wrote: > Re-enable the console device after suspending, causes its cflags, Re-enabling > ispeed and ospeed to be set anew, basing on the values stored in > uport->cons. The issue is that these values are set only once, > when parsing console parameters after boot (see uart_set_options()), Remove "The issue is that" from here and just state: "These values are set only once when parsing console parameters after boot (see uart_set_options())." > next after configuring a port in uart_port_startup() these parameteres parameters > (cflags, ispeed and ospeed) are copied to termios structure and > the orginal one (stored in uport->cons) are cleared, but there is no place original > in code where those fields are checked against 0. > When kernel calls uart_resume_port() and setups console, it copies cflags, > ispeed and ospeed values from uart->cons,but those are alread cleared. missing space after comma. alread -> already > The efect is that console is broken. effect > This patch address this by preserving the cflags, ispeed and Too many "this", don't start with "This patch" but go directly to the point.
śr., 1 mar 2023 o 15:09 Lukasz Majczak <lma@semihalf.com> napisał(a): > > śr., 1 mar 2023 o 13:22 Greg Kroah-Hartman > <gregkh@linuxfoundation.org> napisał(a): > > > > On Wed, Mar 01, 2023 at 10:51:31AM +0100, Lukasz Majczak wrote: > > > śr., 1 mar 2023 o 09:39 Greg Kroah-Hartman > > > <gregkh@linuxfoundation.org> napisał(a): > > > > > > > > On Wed, Mar 01, 2023 at 08:57:51AM +0100, Lukasz Majczak wrote: > > > > > Re-enable the console device after suspending, causes its cflags, > > > > > ispeed and ospeed to be set anew, basing on the values stored in > > > > > uport->cons. The issue is that these values are set only once, > > > > > when parsing console parameters after boot (see uart_set_options()), > > > > > next after configuring a port in uart_port_startup() these parameteres > > > > > (cflags, ispeed and ospeed) are copied to termios structure and > > > > > the orginal one (stored in uport->cons) are cleared, but there is no place > > > > > in code where those fields are checked against 0. > > > > > When kernel calls uart_resume_port() and setups console, it copies cflags, > > > > > ispeed and ospeed values from uart->cons,but those are alread cleared. > > > > > The efect is that console is broken. > > > > > This patch address this by preserving the cflags, ispeed and > > > > > ospeed fields in uart->cons during uart_port_startup(). > > > > > > > > > > Signed-off-by: Lukasz Majczak <lma@semihalf.com> > > > > > Cc: stable@vger.kernel.org > > > > > --- > > > > > drivers/tty/serial/serial_core.c | 3 --- > > > > > 1 file changed, 3 deletions(-) > > > > > > > > > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > > > > > index 2bd32c8ece39..394a05c09d87 100644 > > > > > --- a/drivers/tty/serial/serial_core.c > > > > > +++ b/drivers/tty/serial/serial_core.c > > > > > @@ -225,9 +225,6 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, > > > > > tty->termios.c_cflag = uport->cons->cflag; > > > > > tty->termios.c_ispeed = uport->cons->ispeed; > > > > > tty->termios.c_ospeed = uport->cons->ospeed; > > > > > - uport->cons->cflag = 0; > > > > > - uport->cons->ispeed = 0; > > > > > - uport->cons->ospeed = 0; > > > > > } > > > > > /* > > > > > * Initialise the hardware port settings. > > > > > -- > > > > > 2.39.2.722.g9855ee24e9-goog > > > > > > > > > > > > > What commit id does this fix? > > > > > > > > thanks, > > > > > > > > greg k-h > > > Hi Greg, > > > > > > There are actually two commits that introduce problematic uport flags > > > clearing in uart_startup (for the sake of simplicity I'd ignore the > > > older history): > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.2&id=c7d7abff40c27f82fe78b1091ab3fad69b2546f9 > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.2&id=027b57170bf8bb6999a28e4a5f3d78bf1db0f90c > > > It's 10 years between those 2 and to me it was hard to decide about > > > picking a proper one for the `Fixes:` tag. > > > How would you recommend to proceed wrt applying this patch on the > > > stable releases? > > > > Where do you think this needs to go to? Pick something? > > > > And as you have obviously found this on a device running an older kernel > > version, what kernel tree(s) did you test it on? > > > > thanks, > > > > greg k-h > > As this patch applies without conflict on 4.14, I would suggest 4.14+. > I have tested the patch on chromes-5.15 (cannonlake device). > > Best regards, > Lukasz I have tested my patch also with 4.14 and 6.1 (again chromeos tree). On 4.14 it fixed the issue, but on 6.1 although the console survived the suspend/resume, it is printing different characters than requested - I will try to debug it further. Best regards Lukasz
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 2bd32c8ece39..394a05c09d87 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -225,9 +225,6 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, tty->termios.c_cflag = uport->cons->cflag; tty->termios.c_ispeed = uport->cons->ispeed; tty->termios.c_ospeed = uport->cons->ospeed; - uport->cons->cflag = 0; - uport->cons->ispeed = 0; - uport->cons->ospeed = 0; } /* * Initialise the hardware port settings.
Re-enable the console device after suspending, causes its cflags, ispeed and ospeed to be set anew, basing on the values stored in uport->cons. The issue is that these values are set only once, when parsing console parameters after boot (see uart_set_options()), next after configuring a port in uart_port_startup() these parameteres (cflags, ispeed and ospeed) are copied to termios structure and the orginal one (stored in uport->cons) are cleared, but there is no place in code where those fields are checked against 0. When kernel calls uart_resume_port() and setups console, it copies cflags, ispeed and ospeed values from uart->cons,but those are alread cleared. The efect is that console is broken. This patch address this by preserving the cflags, ispeed and ospeed fields in uart->cons during uart_port_startup(). Signed-off-by: Lukasz Majczak <lma@semihalf.com> Cc: stable@vger.kernel.org --- drivers/tty/serial/serial_core.c | 3 --- 1 file changed, 3 deletions(-)