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serial: core: Introduce callback for start_rx and do stop_rx in suspend only if this callback implementation is present.

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In suspend sequence there is a need to perform stop_rx during suspend
sequence to prevent any asynchronous data over rx line. However this
can cause problem to drivers which dont do re-start_rx during set_termios.

Add new callback start_rx and perform stop_rx only when implementation of
start_rx is present. Also add call to start_rx in resume sequence so that
drivers who come across this problem can make use of this framework.

Fixes: c9d2325cdb92 ("serial: core: Do stop_rx in suspend path for console if console_suspend is disabled")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
Link: https://lore.kernel.org/r/1654627965-1461-2-git-send-email-quic_vnivarth@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vijaya Krishna Nivarthi 2022-06-08 00:22:44 +05:30 committed by Greg Kroah-Hartman
parent e74024b2ec
commit cfab87c2c2
2 changed files with 7 additions and 3 deletions
drivers/tty/serial
serial_core.c
include/linux
serial_core.h

9
drivers/tty/serial/serial_core.c

@ -2214,11 +2214,12 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
/* /*
* Nothing to do if the console is not suspending * Nothing to do if the console is not suspending
* except stop_rx to prevent any asynchronous data * except stop_rx to prevent any asynchronous data
* over RX line. Re-start_rx, when required, is * over RX line. However ensure that we will be
* done by set_termios in resume sequence * able to Re-start_rx later.
*/ */
if (!console_suspend_enabled && uart_console(uport)) { if (!console_suspend_enabled && uart_console(uport)) {
uport->ops->stop_rx(uport); if (uport->ops->start_rx)
uport->ops->stop_rx(uport);
goto unlock; goto unlock;
} }
@ -2310,6 +2311,8 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
if (console_suspend_enabled) if (console_suspend_enabled)
uart_change_pm(state, UART_PM_STATE_ON); uart_change_pm(state, UART_PM_STATE_ON);
uport->ops->set_termios(uport, &termios, NULL); uport->ops->set_termios(uport, &termios, NULL);
if (!console_suspend_enabled && uport->ops->start_rx)
uport->ops->start_rx(uport);
if (console_suspend_enabled) if (console_suspend_enabled)
console_start(uport->cons); console_start(uport->cons);
} }

1
include/linux/serial_core.h

@ -45,6 +45,7 @@ struct uart_ops {
void (*unthrottle)(struct uart_port *); void (*unthrottle)(struct uart_port *);
void (*send_xchar)(struct uart_port *, char ch); void (*send_xchar)(struct uart_port *, char ch);
void (*stop_rx)(struct uart_port *); void (*stop_rx)(struct uart_port *);
void (*start_rx)(struct uart_port *);
void (*enable_ms)(struct uart_port *); void (*enable_ms)(struct uart_port *);
void (*break_ctl)(struct uart_port *, int ctl); void (*break_ctl)(struct uart_port *, int ctl);
int (*startup)(struct uart_port *); int (*startup)(struct uart_port *);