[PATCH 3.13 074/187] serial: core: Preserve termios c_cflag for console resume

Kamal Mostafa kamal at canonical.com
Mon Sep 15 22:08:04 UTC 2014 -stable review patch.  If anyone has any objections, please let me know.


From: Peter Hurley <peter at hurleysoftware.com>

commit ae84db9661cafc63d179e1d985a2c5b841ff0ac4 upstream.

When a tty is opened for the serial console, the termios c_cflag
settings are inherited from the console line settings.
However, if the tty is subsequently closed, the termios settings
are lost. This results in a garbled console if the console is later
suspended and resumed.

Preserve the termios c_cflag for the serial console when the tty
is shutdown; this reflects the most recent line settings.

Fixes: Bugzilla #69751, 'serial console does not wake from S3'
Reported-by: Valerio Vanni <valerio.vanni at inwind.it>
Acked-by: Alan Cox <alan at linux.intel.com>
Signed-off-by: Peter Hurley <peter at hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/tty/serial/serial_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 0f02351..b5180c1 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -235,6 +235,9 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 		 * Turn off DTR and RTS early.
+		if (uart_console(uport) && tty)
+			uport->cons->cflag = tty->termios.c_cflag;
 		if (!tty || (tty->termios.c_cflag & HUPCL))
 			uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);

More information about the kernel-team mailing list